// Returns &inputBuffer[inputLength] if the input buffer is valid.
        /// <summary>
        /// Given an input buffer <paramref name="pInputBuffer"/> of byte length <paramref name="inputLength"/>,
        /// returns a pointer to where the first invalid data appears in <paramref name="pInputBuffer"/>.
        /// </summary>
        /// <remarks>
        /// Returns a pointer to the end of <paramref name="pInputBuffer"/> if the buffer is well-formed.
        /// </remarks>
        public static byte *GetPointerToFirstInvalidByte(byte *pInputBuffer, int inputLength, out int utf16CodeUnitCountAdjustment, out int scalarCountAdjustment)
        {
            Debug.Assert(inputLength >= 0, "Input length must not be negative.");
            Debug.Assert(pInputBuffer != null || inputLength == 0, "Input length must be zero if input buffer pointer is null.");

            // First, try to drain off as many ASCII bytes as we can from the beginning.

            {
                nuint numAsciiBytesCounted = ASCIIUtility32.GetIndexOfFirstNonAsciiByte(pInputBuffer, (uint)inputLength);
                pInputBuffer += numAsciiBytesCounted;

                // Quick check - did we just end up consuming the entire input buffer?
                // If so, short-circuit the remainder of the method.

                inputLength -= (int)numAsciiBytesCounted;
                if (0u >= (uint)inputLength)
                {
                    utf16CodeUnitCountAdjustment = 0;
                    scalarCountAdjustment        = 0;
                    return(pInputBuffer);
                }
            }

#if DEBUG
            // Keep these around for final validation at the end of the method.
            byte *pOriginalInputBuffer = pInputBuffer;
            int   originalInputLength  = inputLength;
#endif

            // Enregistered locals that we'll eventually out to our caller.

            int tempUtf16CodeUnitCountAdjustment = 0;
            int tempScalarCountAdjustment        = 0;

            if (inputLength < sizeof(uint))
            {
                goto ProcessInputOfLessThanDWordSize;
            }

            byte *pFinalPosWhereCanReadDWordFromInputBuffer = pInputBuffer + (uint)inputLength - sizeof(uint);

            // Begin the main loop.

#if DEBUG
            byte *pLastBufferPosProcessed = null; // used for invariant checking in debug builds
#endif

            while (pInputBuffer <= pFinalPosWhereCanReadDWordFromInputBuffer)
            {
                // Read 32 bits at a time. This is enough to hold any possible UTF8-encoded scalar.

                uint thisDWord = Unsafe.ReadUnaligned <uint>(pInputBuffer);

AfterReadDWord:

#if DEBUG
                Debug.Assert(pLastBufferPosProcessed < pInputBuffer, "Algorithm should've made forward progress since last read.");
                pLastBufferPosProcessed = pInputBuffer;
#endif

                // First, check for the common case of all-ASCII bytes.

                if (ASCIIUtility.AllBytesInUInt32AreAscii(thisDWord))
                {
                    // We read an all-ASCII sequence.

                    pInputBuffer += sizeof(uint);

                    // If we saw a sequence of all ASCII, there's a good chance a significant amount of following data is also ASCII.
                    // Below is basically unrolled loops with poor man's vectorization.

                    // Below check is "can I read at least five DWORDs from the input stream?"
                    // n.b. Since we incremented pInputBuffer above the below subtraction may result in a negative value,
                    // hence using nint instead of nuint.

                    if ((nint)(void *)Unsafe.ByteOffset(ref *pInputBuffer, ref *pFinalPosWhereCanReadDWordFromInputBuffer) >= 4 * sizeof(uint))
                    {
                        // We want reads in the inner loop to be aligned. So let's perform a quick
                        // ASCII check of the next 32 bits (4 bytes) now, and if that succeeds bump
                        // the read pointer up to the next aligned address.

                        thisDWord = Unsafe.ReadUnaligned <uint>(pInputBuffer);
                        if (!ASCIIUtility.AllBytesInUInt32AreAscii(thisDWord))
                        {
                            goto AfterReadDWordSkipAllBytesAsciiCheck;
                        }

                        pInputBuffer = (byte *)((nuint)(pInputBuffer + 4) & ~(nuint)3);

                        // At this point, the input buffer offset points to an aligned DWORD. We also know that there's
                        // enough room to read at least four DWORDs from the buffer. (Heed the comment a few lines above:
                        // the original 'if' check confirmed that there were 5 DWORDs before the alignment check, and
                        // the alignment check consumes at most a single DWORD.)

                        byte *pInputBufferFinalPosAtWhichCanSafelyLoop = pFinalPosWhereCanReadDWordFromInputBuffer - 3 * sizeof(uint); // can safely read 4 DWORDs here
                        uint  mask;

                        do
                        {
                            if (Sse2.IsSupported && Bmi1.IsSupported)
                            {
                                // pInputBuffer is 32-bit aligned but not necessary 128-bit aligned, so we're
                                // going to perform an unaligned load. We don't necessarily care about aligning
                                // this because we pessimistically assume we'll encounter non-ASCII data at some
                                // point in the not-too-distant future (otherwise we would've stayed entirely
                                // within the all-ASCII vectorized code at the entry to this method).

                                mask = (uint)Sse2.MoveMask(Sse2.LoadVector128((byte *)pInputBuffer));
                                if (mask != 0)
                                {
                                    goto Sse2LoopTerminatedEarlyDueToNonAsciiData;
                                }
                            }
                            else
                            {
                                if (!ASCIIUtility.AllBytesInUInt32AreAscii(((uint *)pInputBuffer)[0] | ((uint *)pInputBuffer)[1]))
                                {
                                    goto LoopTerminatedEarlyDueToNonAsciiDataInFirstPair;
                                }

                                if (!ASCIIUtility.AllBytesInUInt32AreAscii(((uint *)pInputBuffer)[2] | ((uint *)pInputBuffer)[3]))
                                {
                                    goto LoopTerminatedEarlyDueToNonAsciiDataInSecondPair;
                                }
                            }

                            pInputBuffer += 4 * sizeof(uint); // consumed 4 DWORDs
                        } while (pInputBuffer <= pInputBufferFinalPosAtWhichCanSafelyLoop);

                        continue; // need to perform a bounds check because we might be running out of data

Sse2LoopTerminatedEarlyDueToNonAsciiData:

                        Debug.Assert(BitConverter.IsLittleEndian);
                        Debug.Assert(Sse2.IsSupported);
                        Debug.Assert(Bmi1.IsSupported);

                        // The 'mask' value will have a 0 bit for each ASCII byte we saw and a 1 bit
                        // for each non-ASCII byte we saw. We can count the number of ASCII bytes,
                        // bump our input counter by that amount, and resume processing from the
                        // "the first byte is no longer ASCII" portion of the main loop.

                        Debug.Assert(mask != 0);

                        pInputBuffer += Bmi1.TrailingZeroCount(mask);
                        if (pInputBuffer > pFinalPosWhereCanReadDWordFromInputBuffer)
                        {
                            goto ProcessRemainingBytesSlow;
                        }

                        thisDWord = Unsafe.ReadUnaligned <uint>(pInputBuffer); // no longer guaranteed to be aligned
                        goto BeforeProcessTwoByteSequence;

LoopTerminatedEarlyDueToNonAsciiDataInSecondPair:

                        pInputBuffer += 2 * sizeof(uint); // consumed 2 DWORDs

LoopTerminatedEarlyDueToNonAsciiDataInFirstPair:

                        // We know that there's *at least* two DWORDs of data remaining in the buffer.
                        // We also know that one of them (or both of them) contains non-ASCII data somewhere.
                        // Let's perform a quick check here to bypass the logic at the beginning of the main loop.

                        thisDWord = *(uint *)pInputBuffer; // still aligned here
                        if (ASCIIUtility.AllBytesInUInt32AreAscii(thisDWord))
                        {
                            pInputBuffer += sizeof(uint);          // consumed 1 more DWORD
                            thisDWord     = *(uint *)pInputBuffer; // still aligned here
                        }

                        goto AfterReadDWordSkipAllBytesAsciiCheck;
                    }

                    continue; // not enough data remaining to unroll loop - go back to beginning with bounds checks
                }

AfterReadDWordSkipAllBytesAsciiCheck:

                Debug.Assert(!ASCIIUtility.AllBytesInUInt32AreAscii(thisDWord)); // this should have been handled earlier

                // Next, try stripping off ASCII bytes one at a time.
                // We only handle up to three ASCII bytes here since we handled the four ASCII byte case above.

                {
                    uint numLeadingAsciiBytes = ASCIIUtility.CountNumberOfLeadingAsciiBytesFromUInt32WithSomeNonAsciiData(thisDWord);
                    pInputBuffer += numLeadingAsciiBytes;

                    if (pFinalPosWhereCanReadDWordFromInputBuffer < pInputBuffer)
                    {
                        goto ProcessRemainingBytesSlow; // Input buffer doesn't contain enough data to read a DWORD
                    }
                    else
                    {
                        // The input buffer at the current offset contains a non-ASCII byte.
                        // Read an entire DWORD and fall through to multi-byte consumption logic.
                        thisDWord = Unsafe.ReadUnaligned <uint>(pInputBuffer);
                    }
                }

BeforeProcessTwoByteSequence:

                // At this point, we suspect we're working with a multi-byte code unit sequence,
                // but we haven't yet validated it for well-formedness.

                // The masks and comparands are derived from the Unicode Standard, Table 3-6.
                // Additionally, we need to check for valid byte sequences per Table 3-7.

                // Check the 2-byte case.

                thisDWord -= (BitConverter.IsLittleEndian) ? 0x0000_80C0u : 0xC080_0000u;
                if (0u >= (thisDWord & (BitConverter.IsLittleEndian ? 0x0000_C0E0u : 0xE0C0_0000u)))
                {
                    // Per Table 3-7, valid sequences are:
                    // [ C2..DF ] [ 80..BF ]
                    //
                    // Due to our modification of 'thisDWord' above, this becomes:
                    // [ 02..1F ] [ 00..3F ]
                    //
                    // We've already checked that the leading byte was originally in the range [ C0..DF ]
                    // and that the trailing byte was originally in the range [ 80..BF ], so now we only need
                    // to check that the modified leading byte is >= [ 02 ].

                    if ((BitConverter.IsLittleEndian && (byte)thisDWord < 0x02u) ||
                        (!BitConverter.IsLittleEndian && thisDWord < 0x0200_0000u))
                    {
                        goto Error; // overlong form - leading byte was [ C0 ] or [ C1 ]
                    }

ProcessTwoByteSequenceSkipOverlongFormCheck:

                    // Optimization: If this is a two-byte-per-character language like Cyrillic or Hebrew,
                    // there's a good chance that if we see one two-byte run then there's another two-byte
                    // run immediately after. Let's check that now.

                    // On little-endian platforms, we can check for the two-byte UTF8 mask *and* validate that
                    // the value isn't overlong using a single comparison. On big-endian platforms, we'll need
                    // to validate the mask and validate that the sequence isn't overlong as two separate comparisons.

                    if ((BitConverter.IsLittleEndian && Utf8Utility.UInt32EndsWithValidUtf8TwoByteSequenceLittleEndian(thisDWord)) ||
                        (!BitConverter.IsLittleEndian && (Utf8Utility.UInt32EndsWithUtf8TwoByteMask(thisDWord) && !Utf8Utility.UInt32EndsWithOverlongUtf8TwoByteSequence(thisDWord))))
                    {
                        // We have two runs of two bytes each.
                        pInputBuffer += 4;
                        tempUtf16CodeUnitCountAdjustment -= 2; // 4 UTF-8 code units -> 2 UTF-16 code units (and 2 scalars)

                        if (pInputBuffer <= pFinalPosWhereCanReadDWordFromInputBuffer)
                        {
                            // Optimization: If we read a long run of two-byte sequences, the next sequence is probably
                            // also two bytes. Check for that first before going back to the beginning of the loop.

                            thisDWord = Unsafe.ReadUnaligned <uint>(pInputBuffer);

                            if (BitConverter.IsLittleEndian)
                            {
                                if (Utf8Utility.UInt32BeginsWithValidUtf8TwoByteSequenceLittleEndian(thisDWord))
                                {
                                    // The next sequence is a valid two-byte sequence.
                                    goto ProcessTwoByteSequenceSkipOverlongFormCheck;
                                }
                            }
                            else
                            {
                                if (Utf8Utility.UInt32BeginsWithUtf8TwoByteMask(thisDWord))
                                {
                                    if (Utf8Utility.UInt32BeginsWithOverlongUtf8TwoByteSequence(thisDWord))
                                    {
                                        goto Error; // The next sequence purports to be a 2-byte sequence but is overlong.
                                    }

                                    goto ProcessTwoByteSequenceSkipOverlongFormCheck;
                                }
                            }

                            // If we reached this point, the next sequence is something other than a valid
                            // two-byte sequence, so go back to the beginning of the loop.
                            goto AfterReadDWord;
                        }
                        else
                        {
                            goto ProcessRemainingBytesSlow; // Running out of data - go down slow path
                        }
                    }

                    // The buffer contains a 2-byte sequence followed by 2 bytes that aren't a 2-byte sequence.
                    // Unlikely that a 3-byte sequence would follow a 2-byte sequence, so perhaps remaining
                    // bytes are ASCII?

                    tempUtf16CodeUnitCountAdjustment--; // 2-byte sequence + (some number of ASCII bytes) -> 1 UTF-16 code units (and 1 scalar) [+ trailing]

                    if (Utf8Utility.UInt32ThirdByteIsAscii(thisDWord))
                    {
                        if (Utf8Utility.UInt32FourthByteIsAscii(thisDWord))
                        {
                            pInputBuffer += 4;
                        }
                        else
                        {
                            pInputBuffer += 3;

                            // A two-byte sequence followed by an ASCII byte followed by a non-ASCII byte.
                            // Read in the next DWORD and jump directly to the start of the multi-byte processing block.

                            if (pInputBuffer <= pFinalPosWhereCanReadDWordFromInputBuffer)
                            {
                                thisDWord = Unsafe.ReadUnaligned <uint>(pInputBuffer);
                                goto BeforeProcessTwoByteSequence;
                            }
                        }
                    }
                    else
                    {
                        pInputBuffer += 2;
                    }

                    continue;
                }

                // Check the 3-byte case.
                // We need to restore the C0 leading byte we stripped out earlier, then we can strip out the expected E0 byte.

                thisDWord -= (BitConverter.IsLittleEndian) ? (0x0080_00E0u - 0x0000_00C0u) : (0xE000_8000u - 0xC000_0000u);
                if (0u >= (thisDWord & (BitConverter.IsLittleEndian ? 0x00C0_C0F0u : 0xF0C0_C000u)))
                {
ProcessThreeByteSequenceWithCheck:

                    // We assume the caller has confirmed that the bit pattern is representative of a three-byte
                    // sequence, but it may still be overlong or surrogate. We need to check for these possibilities.
                    //
                    // Per Table 3-7, valid sequences are:
                    // [   E0   ] [ A0..BF ] [ 80..BF ]
                    // [ E1..EC ] [ 80..BF ] [ 80..BF ]
                    // [   ED   ] [ 80..9F ] [ 80..BF ]
                    // [ EE..EF ] [ 80..BF ] [ 80..BF ]
                    //
                    // Big-endian examples of using the above validation table:
                    // E0A0 = 1110 0000 1010 0000 => invalid (overlong ) patterns are 1110 0000 100# ####
                    // ED9F = 1110 1101 1001 1111 => invalid (surrogate) patterns are 1110 1101 101# ####
                    // If using the bitmask ......................................... 0000 1111 0010 0000 (=0F20),
                    // Then invalid (overlong) patterns match the comparand ......... 0000 0000 0000 0000 (=0000),
                    // And invalid (surrogate) patterns match the comparand ......... 0000 1101 0010 0000 (=0D20).
                    //
                    // It's ok if the caller has manipulated 'thisDWord' (e.g., by subtracting 0xE0 or 0x80)
                    // as long as they haven't touched the bits we're about to use in our mask checking below.

                    if (BitConverter.IsLittleEndian)
                    {
                        // The "overlong or surrogate" check can be implemented using a single jump, but there's
                        // some overhead to moving the bits into the correct locations in order to perform the
                        // correct comparison, and in practice the processor's branch prediction capability is
                        // good enough that we shouldn't bother. So we'll use two jumps instead.

                        // Can't extract this check into its own helper method because JITter produces suboptimal
                        // assembly, even with aggressive inlining.

                        // Code below becomes 5 instructions: test, jz, lea, test, jz

                        if ((0u >= (thisDWord & 0x0000_200Fu)) || (0u >= ((thisDWord - 0x0000_200Du) & 0x0000_200Fu)))
                        {
                            goto Error; // overlong or surrogate
                        }
                    }
                    else
                    {
                        if ((0u >= (thisDWord & 0x0F20_0000u)) || (0u >= ((thisDWord - 0x0D20_0000u) & 0x0F20_0000u)))
                        {
                            goto Error; // overlong or surrogate
                        }
                    }

ProcessSingleThreeByteSequenceSkipOverlongAndSurrogateChecks:

                    // Occasionally one-off ASCII characters like spaces, periods, or newlines will make their way
                    // in to the text. If this happens strip it off now before seeing if the next character
                    // consists of three code units.

                    // Branchless: consume a 3-byte UTF-8 sequence and optionally an extra ASCII byte hanging off the end

                    nint asciiAdjustment;
                    if (BitConverter.IsLittleEndian)
                    {
                        asciiAdjustment = (int)thisDWord >> 31; // smear most significant bit across entire value
                    }
                    else
                    {
                        asciiAdjustment = (nint)(sbyte)thisDWord >> 7; // smear most significant bit of least significant byte across entire value
                    }

                    // asciiAdjustment = 0 if fourth byte is ASCII; -1 otherwise

                    // Please *DO NOT* reorder the below two lines. It provides extra defense in depth in case this method
                    // is ever changed such that pInputBuffer becomes a 'ref byte' instead of a simple 'byte*'. It's valid
                    // to add 4 before backing up since we already checked previously that the input buffer contains at
                    // least a DWORD's worth of data, so we're not going to run past the end of the buffer where the GC can
                    // no longer track the reference. However, we can't back up before adding 4, since we might back up to
                    // before the start of the buffer, and the GC isn't guaranteed to be able to track this.

                    pInputBuffer += 4;                     // optimistically, assume consumed a 3-byte UTF-8 sequence plus an extra ASCII byte
                    pInputBuffer += asciiAdjustment;       // back up if we didn't actually consume an ASCII byte

                    tempUtf16CodeUnitCountAdjustment -= 2; // 3 (or 4) UTF-8 bytes -> 1 (or 2) UTF-16 code unit (and 1 [or 2] scalar)

SuccessfullyProcessedThreeByteSequence:

                    if (PlatformDependent.Is64BitProcess && BitConverter.IsLittleEndian)
                    {
                        // x64 little-endian optimization: A three-byte character could indicate CJK text,
                        // which makes it likely that the character following this one is also CJK.
                        // We'll try to process several three-byte sequences at a time.

                        // The check below is really "can we read 9 bytes from the input buffer?" since 'pFinalPos...' is already offset
                        // n.b. The subtraction below could result in a negative value (since we advanced pInputBuffer above), so
                        // use nint instead of nuint.

                        if ((nint)(pFinalPosWhereCanReadDWordFromInputBuffer - pInputBuffer) >= 5)
                        {
                            ulong thisQWord = Unsafe.ReadUnaligned <ulong>(pInputBuffer);

                            // Stage the next 32 bits into 'thisDWord' so that it's ready for us in case we need to jump backward
                            // to a previous location in the loop. This offers defense against reading main memory again (which may
                            // have been modified and could lead to a race condition).

                            thisDWord = (uint)thisQWord;

                            // Is this three 3-byte sequences in a row?
                            // thisQWord = [ 10yyyyyy 1110zzzz | 10xxxxxx 10yyyyyy 1110zzzz | 10xxxxxx 10yyyyyy 1110zzzz ] [ 10xxxxxx ]
                            //               ---- CHAR 3  ----   --------- CHAR 2 ---------   --------- CHAR 1 ---------     -CHAR 3-
                            if ((thisQWord & 0xC0F0_C0C0_F0C0_C0F0ul) == 0x80E0_8080_E080_80E0ul && Utf8Utility.IsUtf8ContinuationByte(in pInputBuffer[8]))
                            {
                                // Saw a proper bitmask for three incoming 3-byte sequences, perform the
                                // overlong and surrogate sequence checking now.

                                // Check the first character.
                                // If the first character is overlong or a surrogate, fail immediately.

                                if ((0u >= ((uint)thisQWord & 0x200Fu)) || (0u >= (((uint)thisQWord - 0x200Du) & 0x200Fu)))
                                {
                                    goto Error;
                                }

                                // Check the second character.
                                // At this point, we now know the first three bytes represent a well-formed sequence.
                                // If there's an error beyond here, we'll jump back to the "process three known good bytes"
                                // logic.

                                thisQWord >>= 24;
                                if ((0u >= ((uint)thisQWord & 0x200Fu)) || (0u >= (((uint)thisQWord - 0x200Du) & 0x200Fu)))
                                {
                                    goto ProcessSingleThreeByteSequenceSkipOverlongAndSurrogateChecks;
                                }

                                // Check the third character (we already checked that it's followed by a continuation byte).

                                thisQWord >>= 24;
                                if ((0u >= ((uint)thisQWord & 0x200Fu)) || (0u >= (((uint)thisQWord - 0x200Du) & 0x200Fu)))
                                {
                                    goto ProcessSingleThreeByteSequenceSkipOverlongAndSurrogateChecks;
                                }

                                pInputBuffer += 9;
                                tempUtf16CodeUnitCountAdjustment -= 6; // 9 UTF-8 bytes -> 3 UTF-16 code units (and 3 scalars)

                                goto SuccessfullyProcessedThreeByteSequence;
                            }

                            // Is this two 3-byte sequences in a row?
                            // thisQWord = [ ######## ######## | 10xxxxxx 10yyyyyy 1110zzzz | 10xxxxxx 10yyyyyy 1110zzzz ]
                            //                                   --------- CHAR 2 ---------   --------- CHAR 1 ---------
                            if ((thisQWord & 0xC0C0_F0C0_C0F0ul) == 0x8080_E080_80E0ul)
                            {
                                // Saw a proper bitmask for two incoming 3-byte sequences, perform the
                                // overlong and surrogate sequence checking now.

                                // Check the first character.
                                // If the first character is overlong or a surrogate, fail immediately.

                                if ((0u >= ((uint)thisQWord & 0x200Fu)) || (0u >= (((uint)thisQWord - 0x200Du) & 0x200Fu)))
                                {
                                    goto Error;
                                }

                                // Check the second character.
                                // At this point, we now know the first three bytes represent a well-formed sequence.
                                // If there's an error beyond here, we'll jump back to the "process three known good bytes"
                                // logic.

                                thisQWord >>= 24;
                                if ((0u >= ((uint)thisQWord & 0x200Fu)) || (0u >= (((uint)thisQWord - 0x200Du) & 0x200Fu)))
                                {
                                    goto ProcessSingleThreeByteSequenceSkipOverlongAndSurrogateChecks;
                                }

                                pInputBuffer += 6;
                                tempUtf16CodeUnitCountAdjustment -= 4; // 6 UTF-8 bytes -> 2 UTF-16 code units (and 2 scalars)

                                // The next byte in the sequence didn't have a 3-byte marker, so it's probably
                                // an ASCII character. Jump back to the beginning of loop processing.

                                continue;
                            }

                            if (Utf8Utility.UInt32BeginsWithUtf8ThreeByteMask(thisDWord))
                            {
                                // A single three-byte sequence.
                                goto ProcessThreeByteSequenceWithCheck;
                            }
                            else
                            {
                                // Not a three-byte sequence; perhaps ASCII?
                                goto AfterReadDWord;
                            }
                        }
                    }

                    if (pInputBuffer <= pFinalPosWhereCanReadDWordFromInputBuffer)
                    {
                        thisDWord = Unsafe.ReadUnaligned <uint>(pInputBuffer);

                        // Optimization: A three-byte character could indicate CJK text, which makes it likely
                        // that the character following this one is also CJK. We'll check for a three-byte sequence
                        // marker now and jump directly to three-byte sequence processing if we see one, skipping
                        // all of the logic at the beginning of the loop.

                        if (Utf8Utility.UInt32BeginsWithUtf8ThreeByteMask(thisDWord))
                        {
                            goto ProcessThreeByteSequenceWithCheck; // Found another [not yet validated] three-byte sequence; process
                        }
                        else
                        {
                            goto AfterReadDWord; // Probably ASCII punctuation or whitespace; go back to start of loop
                        }
                    }
                    else
                    {
                        goto ProcessRemainingBytesSlow; // Running out of data
                    }
                }

                // Assume the 4-byte case, but we need to validate.

                if (BitConverter.IsLittleEndian)
                {
                    thisDWord &= 0xC0C0_FFFFu;

                    // After the above modifications earlier in this method, we expect 'thisDWord'
                    // to have the structure [ 10000000 00000000 00uuzzzz 00010uuu ]. We'll now
                    // perform two checks to confirm this. The first will verify the
                    // [ 10000000 00000000 00###### ######## ] structure by taking advantage of two's
                    // complement representation to perform a single *signed* integer check.

                    if ((int)thisDWord > unchecked ((int)0x8000_3FFF))
                    {
                        goto Error; // didn't have three trailing bytes
                    }

                    // Now we want to confirm that 0x01 <= uuuuu (otherwise this is an overlong encoding)
                    // and that uuuuu <= 0x10 (otherwise this is an out-of-range encoding).

                    thisDWord = BitOperations.RotateRight(thisDWord, 8);

                    // Now, thisDWord = [ 00010uuu 10000000 00000000 00uuzzzz ].
                    // The check is now a simple add / cmp / jcc combo.

                    if (!UnicodeUtility.IsInRangeInclusive(thisDWord, 0x1080_0010u, 0x1480_000Fu))
                    {
                        goto Error; // overlong or out-of-range
                    }
                }
                else
                {
                    thisDWord -= 0x80u;

                    // After the above modifications earlier in this method, we expect 'thisDWord'
                    // to have the structure [ 00010uuu 00uuzzzz 00yyyyyy 00xxxxxx ]. We'll now
                    // perform two checks to confirm this. The first will verify the
                    // [ ######## 00###### 00###### 00###### ] structure.

                    if ((thisDWord & 0x00C0_C0C0u) != 0)
                    {
                        goto Error; // didn't have three trailing bytes
                    }

                    // Now we want to confirm that 0x01 <= uuuuu (otherwise this is an overlong encoding)
                    // and that uuuuu <= 0x10 (otherwise this is an out-of-range encoding).
                    // This is a simple range check. (We don't care about the low two bytes.)

                    if (!UnicodeUtility.IsInRangeInclusive(thisDWord, 0x1010_0000u, 0x140F_FFFFu))
                    {
                        goto Error; // overlong or out-of-range
                    }
                }

                // Validation of 4-byte case complete.

                pInputBuffer += 4;
                tempUtf16CodeUnitCountAdjustment -= 2; // 4 UTF-8 bytes -> 2 UTF-16 code units
                tempScalarCountAdjustment--;           // 2 UTF-16 code units -> 1 scalar

                continue;                              // go back to beginning of loop for processing
            }

            goto ProcessRemainingBytesSlow;

ProcessInputOfLessThanDWordSize:

            Debug.Assert(inputLength < 4);
            nuint inputBufferRemainingBytes = (uint)inputLength;
            goto ProcessSmallBufferCommon;

ProcessRemainingBytesSlow:

            inputBufferRemainingBytes = (nuint)(void *)Unsafe.ByteOffset(ref *pInputBuffer, ref *pFinalPosWhereCanReadDWordFromInputBuffer) + 4;

ProcessSmallBufferCommon:

            Debug.Assert(inputBufferRemainingBytes < 4);
            while (inputBufferRemainingBytes > 0)
            {
                uint firstByte = pInputBuffer[0];

                if ((byte)firstByte < 0x80u)
                {
                    // 1-byte (ASCII) case
                    pInputBuffer++;
                    inputBufferRemainingBytes--;
                    continue;
                }
                else if (inputBufferRemainingBytes >= 2)
                {
                    uint secondByte = pInputBuffer[1]; // typed as 32-bit since we perform arithmetic (not just comparisons) on this value
                    if ((byte)firstByte < 0xE0u)
                    {
                        // 2-byte case
                        if ((byte)firstByte >= 0xC2u && Utf8Utility.IsLowByteUtf8ContinuationByte(secondByte))
                        {
                            pInputBuffer += 2;
                            tempUtf16CodeUnitCountAdjustment--; // 2 UTF-8 bytes -> 1 UTF-16 code unit (and 1 scalar)
                            inputBufferRemainingBytes -= 2;
                            continue;
                        }
                    }
                    else if (inputBufferRemainingBytes >= 3)
                    {
                        if ((byte)firstByte < 0xF0u)
                        {
                            if ((byte)firstByte == 0xE0u)
                            {
                                if (!UnicodeUtility.IsInRangeInclusive(secondByte, 0xA0u, 0xBFu))
                                {
                                    goto Error; // overlong encoding
                                }
                            }
                            else if ((byte)firstByte == 0xEDu)
                            {
                                if (!UnicodeUtility.IsInRangeInclusive(secondByte, 0x80u, 0x9Fu))
                                {
                                    goto Error; // would be a UTF-16 surrogate code point
                                }
                            }
                            else
                            {
                                if (!Utf8Utility.IsLowByteUtf8ContinuationByte(secondByte))
                                {
                                    goto Error; // first trailing byte doesn't have proper continuation marker
                                }
                            }

                            if (Utf8Utility.IsUtf8ContinuationByte(in pInputBuffer[2]))
                            {
                                pInputBuffer += 3;
                                tempUtf16CodeUnitCountAdjustment -= 2; // 3 UTF-8 bytes -> 2 UTF-16 code units (and 2 scalars)
                                inputBufferRemainingBytes        -= 3;
                                continue;
                            }
                        }
                    }
                }

                // Error - no match.

                goto Error;
            }

            // If we reached this point, we're out of data, and we saw no bad UTF8 sequence.

#if DEBUG
            // Quick check that for the success case we're going to fulfill our contract of returning &inputBuffer[inputLength].
            Debug.Assert(pOriginalInputBuffer + originalInputLength == pInputBuffer, "About to return an unexpected value.");
#endif

Error:

            // Report back to our caller how far we got before seeing invalid data.
            // (Also used for normal termination when falling out of the loop above.)

            utf16CodeUnitCountAdjustment = tempUtf16CodeUnitCountAdjustment;
            scalarCountAdjustment        = tempScalarCountAdjustment;
            return(pInputBuffer);
        }
        // Returns &inputBuffer[inputLength] if the input buffer is valid.
        /// <summary>
        /// Given an input buffer <paramref name="pInputBuffer"/> of char length <paramref name="inputLength"/>,
        /// returns a pointer to where the first invalid data appears in <paramref name="pInputBuffer"/>.
        /// </summary>
        /// <remarks>
        /// Returns a pointer to the end of <paramref name="pInputBuffer"/> if the buffer is well-formed.
        /// </remarks>
        public static char *GetPointerToFirstInvalidChar(char *pInputBuffer, int inputLength, out long utf8CodeUnitCountAdjustment, out int scalarCountAdjustment)
        {
            Debug.Assert(inputLength >= 0, "Input length must not be negative.");
            Debug.Assert(pInputBuffer != null || inputLength == 0, "Input length must be zero if input buffer pointer is null.");

            // First, we'll handle the common case of all-ASCII. If this is able to
            // consume the entire buffer, we'll skip the remainder of this method's logic.

            int numAsciiCharsConsumedJustNow = (int)ASCIIUtility32.GetIndexOfFirstNonAsciiChar(pInputBuffer, (uint)inputLength);

            Debug.Assert(0 <= numAsciiCharsConsumedJustNow && numAsciiCharsConsumedJustNow <= inputLength);

            pInputBuffer += (uint)numAsciiCharsConsumedJustNow;
            inputLength  -= numAsciiCharsConsumedJustNow;

            if (0u >= (uint)inputLength)
            {
                utf8CodeUnitCountAdjustment = 0;
                scalarCountAdjustment       = 0;
                return(pInputBuffer);
            }

            // If we got here, it means we saw some non-ASCII data, so within our
            // vectorized code paths below we'll handle all non-surrogate UTF-16
            // code points branchlessly. We'll only branch if we see surrogates.
            //
            // We still optimistically assume the data is mostly ASCII. This means that the
            // number of UTF-8 code units and the number of scalars almost matches the number
            // of UTF-16 code units. As we go through the input and find non-ASCII
            // characters, we'll keep track of these "adjustment" fixups. To get the
            // total number of UTF-8 code units required to encode the input data, add
            // the UTF-8 code unit count adjustment to the number of UTF-16 code units
            // seen.  To get the total number of scalars present in the input data,
            // add the scalar count adjustment to the number of UTF-16 code units seen.

            long tempUtf8CodeUnitCountAdjustment = 0;
            int  tempScalarCountAdjustment       = 0;

            if (Sse2.IsSupported)
            {
                if (inputLength >= Vector128 <ushort> .Count)
                {
                    Vector128 <ushort> vector0080 = Vector128.Create((ushort)0x80);
                    Vector128 <ushort> vectorA800 = Vector128.Create((ushort)0xA800);
                    Vector128 <short>  vector8800 = Vector128.Create(unchecked ((short)0x8800));
                    Vector128 <ushort> vectorZero = Vector128 <ushort> .Zero;

                    do
                    {
                        Vector128 <ushort> utf16Data = Sse2.LoadVector128((ushort *)pInputBuffer); // unaligned
                        uint mask;

                        // The 'charIsNonAscii' vector we're about to build will have the 0x8000 or the 0x0080
                        // bit set (but not both!) only if the corresponding input char is non-ASCII. Which of
                        // the two bits is set doesn't matter, as will be explained in the diagram a few lines
                        // below.

                        Vector128 <ushort> charIsNonAscii;
                        if (Sse41.IsSupported)
                        {
                            // sets 0x0080 bit if corresponding char element is >= 0x0080
                            charIsNonAscii = Sse41.Min(utf16Data, vector0080);
                        }
                        else
                        {
                            // sets 0x8000 bit if corresponding char element is >= 0x0080
                            charIsNonAscii = Sse2.AndNot(vector0080, Sse2.Subtract(vectorZero, Sse2.ShiftRightLogical(utf16Data, 7)));
                        }

#if DEBUG
                        // Quick check to ensure we didn't accidentally set both 0x8080 bits in any element.
                        uint debugMask = (uint)Sse2.MoveMask(charIsNonAscii.AsByte());
                        Debug.Assert((debugMask & (debugMask << 1)) == 0, "Two set bits shouldn't occur adjacent to each other in this mask.");
#endif // DEBUG

                        // sets 0x8080 bits if corresponding char element is >= 0x0800
                        Vector128 <ushort> charIsThreeByteUtf8Encoded = Sse2.Subtract(vectorZero, Sse2.ShiftRightLogical(utf16Data, 11));

                        mask = (uint)Sse2.MoveMask(Sse2.Or(charIsNonAscii, charIsThreeByteUtf8Encoded).AsByte());

                        // Each odd bit of mask will be 1 only if the char was >= 0x0080,
                        // and each even bit of mask will be 1 only if the char was >= 0x0800.
                        //
                        // Example for UTF-16 input "[ 0123 ] [ 1234 ] ...":
                        //
                        //            ,-- set if char[1] is non-ASCII
                        //            |   ,-- set if char[0] is non-ASCII
                        //            v   v
                        // mask = ... 1 1 1 0
                        //              ^   ^-- set if char[0] is >= 0x0800
                        //              `-- set if char[1] is >= 0x0800
                        //
                        // (If the SSE4.1 code path is taken above, the meaning of the odd and even
                        // bits are swapped, but the logic below otherwise holds.)
                        //
                        // This means we can popcnt the number of set bits, and the result is the
                        // number of *additional* UTF-8 bytes that each UTF-16 code unit requires as
                        // it expands. This results in the wrong count for UTF-16 surrogate code
                        // units (we just counted that each individual code unit expands to 3 bytes,
                        // but in reality a well-formed UTF-16 surrogate pair expands to 4 bytes).
                        // We'll handle this in just a moment.
                        //
                        // For now, compute the popcnt but squirrel it away. We'll fold it in to the
                        // cumulative UTF-8 adjustment factor once we determine that there are no
                        // unpaired surrogates in our data. (Unpaired surrogates would invalidate
                        // our computed result and we'd have to throw it away.)

                        uint popcnt = (uint)BitOperations.PopCount(mask);

                        // Surrogates need to be special-cased for two reasons: (a) we need
                        // to account for the fact that we over-counted in the addition above;
                        // and (b) they require separate validation.

                        utf16Data = Sse2.Add(utf16Data, vectorA800);
                        mask      = (uint)Sse2.MoveMask(Sse2.CompareLessThan(utf16Data.AsInt16(), vector8800).AsByte());

                        if (mask != 0)
                        {
                            // There's at least one UTF-16 surrogate code unit present.
                            // Since we performed a pmovmskb operation on the result of a 16-bit pcmpgtw,
                            // the resulting bits of 'mask' will occur in pairs:
                            // - 00 if the corresponding UTF-16 char was not a surrogate code unit;
                            // - 11 if the corresponding UTF-16 char was a surrogate code unit.
                            //
                            // A UTF-16 high/low surrogate code unit has the bit pattern [ 11011q## ######## ],
                            // where # is any bit; q = 0 represents a high surrogate, and q = 1 represents
                            // a low surrogate. Since we added 0xA800 in the vectorized operation above,
                            // our surrogate pairs will now have the bit pattern [ 10000q## ######## ].
                            // If we logical right-shift each word by 3, we'll end up with the bit pattern
                            // [ 00010000 q####### ], which means that we can immediately use pmovmskb to
                            // determine whether a given char was a high or a low surrogate.
                            //
                            // Therefore the resulting bits of 'mask2' will occur in pairs:
                            // - 00 if the corresponding UTF-16 char was a high surrogate code unit;
                            // - 01 if the corresponding UTF-16 char was a low surrogate code unit;
                            // - ## (garbage) if the corresponding UTF-16 char was not a surrogate code unit.
                            //   Since 'mask' already has 00 in these positions (since the corresponding char
                            //   wasn't a surrogate), "mask AND mask2 == 00" holds for these positions.

                            uint mask2 = (uint)Sse2.MoveMask(Sse2.ShiftRightLogical(utf16Data, 3).AsByte());

                            // 'lowSurrogatesMask' has its bits occur in pairs:
                            // - 01 if the corresponding char was a low surrogate char,
                            // - 00 if the corresponding char was a high surrogate char or not a surrogate at all.

                            uint lowSurrogatesMask = mask2 & mask;

                            // 'highSurrogatesMask' has its bits occur in pairs:
                            // - 01 if the corresponding char was a high surrogate char,
                            // - 00 if the corresponding char was a low surrogate char or not a surrogate at all.

                            uint highSurrogatesMask = (mask2 ^ 0b_0101_0101_0101_0101u /* flip all even-numbered bits 00 <-> 01 */) & mask;

                            Debug.Assert((highSurrogatesMask & lowSurrogatesMask) == 0,
                                         "A char cannot simultaneously be both a high and a low surrogate char.");

                            Debug.Assert(((highSurrogatesMask | lowSurrogatesMask) & 0b_1010_1010_1010_1010u) == 0,
                                         "Only even bits (no odd bits) of the masks should be set.");

                            // Now check that each high surrogate is followed by a low surrogate and that each
                            // low surrogate follows a high surrogate. We make an exception for the case where
                            // the final char of the vector is a high surrogate, since we can't perform validation
                            // on it until the next iteration of the loop when we hope to consume the matching
                            // low surrogate.

                            highSurrogatesMask <<= 2;
                            if ((ushort)highSurrogatesMask != lowSurrogatesMask)
                            {
                                goto NonVectorizedLoop; // error: mismatched surrogate pair; break out of vectorized logic
                            }

                            if (highSurrogatesMask > ushort.MaxValue)
                            {
                                // There was a standalone high surrogate at the end of the vector.
                                // We'll adjust our counters so that we don't consider this char consumed.

                                highSurrogatesMask = (ushort)highSurrogatesMask; // don't allow stray high surrogate to be consumed by popcnt
                                popcnt            -= 2;                          // the '0xC000_0000' bits in the original mask are shifted out and discarded, so account for that here
                                pInputBuffer--;
                                inputLength++;
                            }

                            // If we're 64-bit, we can perform the zero-extension of the surrogate pairs count for
                            // free right now, saving the extension step a few lines below. If we're 32-bit, the
                            // convertion to nuint immediately below is a no-op, and we'll pay the cost of the real
                            // 64 -bit extension a few lines below.
                            nuint surrogatePairsCountNuint = (uint)BitOperations.PopCount(highSurrogatesMask);

                            // 2 UTF-16 chars become 1 Unicode scalar

                            tempScalarCountAdjustment -= (int)surrogatePairsCountNuint;

                            // Since each surrogate code unit was >= 0x0800, we eagerly assumed
                            // it'd be encoded as 3 UTF-8 code units, so our earlier popcnt computation
                            // assumes that the pair is encoded as 6 UTF-8 code units. Since each
                            // pair is in reality only encoded as 4 UTF-8 code units, we need to
                            // perform this adjustment now.

                            if (PlatformDependent.Is64BitProcess)
                            {
                                // Since we've already zero-extended surrogatePairsCountNuint, we can directly
                                // sub + sub. It's more efficient than shl + sub.
                                tempUtf8CodeUnitCountAdjustment -= (long)surrogatePairsCountNuint;
                                tempUtf8CodeUnitCountAdjustment -= (long)surrogatePairsCountNuint;
                            }
                            else
                            {
                                // Take the hit of the 64-bit extension now.
                                tempUtf8CodeUnitCountAdjustment -= 2 * (uint)surrogatePairsCountNuint;
                            }
                        }

                        tempUtf8CodeUnitCountAdjustment += popcnt;
                        pInputBuffer += Vector128 <ushort> .Count;
                        inputLength  -= Vector128 <ushort> .Count;
                    } while (inputLength >= Vector128 <ushort> .Count);
                }
            }
            else if (Vector.IsHardwareAccelerated)
            {
                if (inputLength >= Vector <ushort> .Count)
                {
                    Vector <ushort> vector0080 = new Vector <ushort>(0x0080);
                    Vector <ushort> vector0400 = new Vector <ushort>(0x0400);
                    Vector <ushort> vector0800 = new Vector <ushort>(0x0800);
                    Vector <ushort> vectorD800 = new Vector <ushort>(0xD800);

                    do
                    {
                        // The 'twoOrMoreUtf8Bytes' and 'threeOrMoreUtf8Bytes' vectors will contain
                        // elements whose values are 0xFFFF (-1 as signed word) iff the corresponding
                        // UTF-16 code unit was >= 0x0080 and >= 0x0800, respectively. By summing these
                        // vectors, each element of the sum will contain one of three values:
                        //
                        // 0x0000 ( 0) = original char was 0000..007F
                        // 0xFFFF (-1) = original char was 0080..07FF
                        // 0xFFFE (-2) = original char was 0800..FFFF
                        //
                        // We'll negate them to produce a value 0..2 for each element, then sum all the
                        // elements together to produce the number of *additional* UTF-8 code units
                        // required to represent this UTF-16 data. This is similar to the popcnt step
                        // performed by the SSE2 code path. This will overcount surrogates, but we'll
                        // handle that shortly.

                        Vector <ushort> utf16Data            = Unsafe.ReadUnaligned <Vector <ushort> >(pInputBuffer);
                        Vector <ushort> twoOrMoreUtf8Bytes   = Vector.GreaterThanOrEqual(utf16Data, vector0080);
                        Vector <ushort> threeOrMoreUtf8Bytes = Vector.GreaterThanOrEqual(utf16Data, vector0800);
                        Vector <nuint>  sumVector            = (Vector <nuint>)(Vector <ushort> .Zero - twoOrMoreUtf8Bytes - threeOrMoreUtf8Bytes);

                        // We'll try summing by a natural word (rather than a 16-bit word) at a time,
                        // which should halve the number of operations we must perform.

                        nuint popcnt = 0;
                        for (int i = 0; i < Vector <nuint> .Count; i++)
                        {
                            popcnt += sumVector[i];
                        }

                        uint popcnt32 = (uint)popcnt;
                        if (PlatformDependent.Is64BitProcess)
                        {
                            popcnt32 += (uint)(popcnt >> 32);
                        }

                        // As in the SSE4.1 paths, compute popcnt but don't fold it in until we
                        // know there aren't any unpaired surrogates in the input data.

                        popcnt32 = (ushort)popcnt32 + (popcnt32 >> 16);

                        // Now check for surrogates.

                        utf16Data -= vectorD800;
                        Vector <ushort> surrogateChars = Vector.LessThan(utf16Data, vector0800);
                        if (surrogateChars != Vector <ushort> .Zero)
                        {
                            // There's at least one surrogate (high or low) UTF-16 code unit in
                            // the vector. We'll build up additional vectors: 'highSurrogateChars'
                            // and 'lowSurrogateChars', where the elements are 0xFFFF iff the original
                            // UTF-16 code unit was a high or low surrogate, respectively.

                            Vector <ushort> highSurrogateChars = Vector.LessThan(utf16Data, vector0400);
                            Vector <ushort> lowSurrogateChars  = Vector.AndNot(surrogateChars, highSurrogateChars);

                            // We want to make sure that each high surrogate code unit is followed by
                            // a low surrogate code unit and each low surrogate code unit follows a
                            // high surrogate code unit. Since we don't have an equivalent of pmovmskb
                            // or palignr available to us, we'll do this as a loop. We won't look at
                            // the very last high surrogate char element since we don't yet know if
                            // the next vector read will have a low surrogate char element.

                            if (lowSurrogateChars[0] != 0)
                            {
                                goto Error; // error: start of buffer contains standalone low surrogate char
                            }

                            ushort surrogatePairsCount = 0;
                            for (int i = 0; i < Vector <ushort> .Count - 1; i++)
                            {
                                surrogatePairsCount -= highSurrogateChars[i]; // turns into +1 or +0
                                if (highSurrogateChars[i] != lowSurrogateChars[i + 1])
                                {
                                    goto NonVectorizedLoop; // error: mismatched surrogate pair; break out of vectorized logic
                                }
                            }

                            if (highSurrogateChars[Vector <ushort> .Count - 1] != 0)
                            {
                                // There was a standalone high surrogate at the end of the vector.
                                // We'll adjust our counters so that we don't consider this char consumed.

                                pInputBuffer--;
                                inputLength++;
                                popcnt32 -= 2;
                            }

                            nint surrogatePairsCountNint = (nint)surrogatePairsCount; // zero-extend to native int size

                            // 2 UTF-16 chars become 1 Unicode scalar

                            tempScalarCountAdjustment -= (int)surrogatePairsCountNint;

                            // Since each surrogate code unit was >= 0x0800, we eagerly assumed
                            // it'd be encoded as 3 UTF-8 code units. Each surrogate half is only
                            // encoded as 2 UTF-8 code units (for 4 UTF-8 code units total),
                            // so we'll adjust this now.

                            tempUtf8CodeUnitCountAdjustment -= surrogatePairsCountNint;
                            tempUtf8CodeUnitCountAdjustment -= surrogatePairsCountNint;
                        }

                        tempUtf8CodeUnitCountAdjustment += popcnt32;
                        pInputBuffer += Vector <ushort> .Count;
                        inputLength  -= Vector <ushort> .Count;
                    } while (inputLength >= Vector <ushort> .Count);
                }
            }

NonVectorizedLoop:

            // Vectorization isn't supported on our current platform, or the input was too small to benefit
            // from vectorization, or we saw invalid UTF-16 data in the vectorized code paths and need to
            // drain remaining valid chars before we report failure.

            for (; inputLength > 0; pInputBuffer++, inputLength--)
            {
                uint thisChar = pInputBuffer[0];
                if (thisChar <= 0x7F)
                {
                    continue;
                }

                // Bump adjustment by +1 for U+0080..U+07FF; by +2 for U+0800..U+FFFF.
                // This optimistically assumes no surrogates, which we'll handle shortly.

                tempUtf8CodeUnitCountAdjustment += (thisChar + 0x0001_F800u) >> 16;

                if (!UnicodeUtility.IsSurrogateCodePoint(thisChar))
                {
                    continue;
                }

                // Found a surrogate char. Back out the adjustment we made above, then
                // try to consume the entire surrogate pair all at once. We won't bother
                // trying to interpret the surrogate pair as a scalar value; we'll only
                // validate that its bit pattern matches what's expected for a surrogate pair.

                tempUtf8CodeUnitCountAdjustment -= 2;

                if (inputLength == 1)
                {
                    goto Error; // input buffer too small to read a surrogate pair
                }

                thisChar = Unsafe.ReadUnaligned <uint>(pInputBuffer);
                if (((thisChar - (BitConverter.IsLittleEndian ? 0xDC00_D800u : 0xD800_DC00u)) & 0xFC00_FC00u) != 0)
                {
                    goto Error; // not a well-formed surrogate pair
                }

                tempScalarCountAdjustment--;          // 2 UTF-16 code units -> 1 scalar
                tempUtf8CodeUnitCountAdjustment += 2; // 2 UTF-16 code units -> 4 UTF-8 code units

                pInputBuffer++;                       // consumed one extra char
                inputLength--;
            }

Error:

            // Also used for normal return.

            utf8CodeUnitCountAdjustment = tempUtf8CodeUnitCountAdjustment;
            scalarCountAdjustment       = tempScalarCountAdjustment;
            return(pInputBuffer);
        }