// Section A8.8.64, page A8-410 (LDR encoding A1)
private (uint reg_t, ushort imm)? getLdrLit(uint inst)
{
if (inst.Bits(16, 16) != 0b_1110_0101_1001_1111)
{
return(null);
}
var reg_t = inst.Bits(12, 4);
var imm12 = inst.Bits(0, 12);
return(reg_t, (ushort)imm12);
}
// Section A8.8.66, page A8-414 (LDR encoding A1)
// Specifically LDR Rx, [Ry, Rz]
private (uint reg_t, uint reg_n, uint reg_m)? getLdrReg(uint inst)
{
if (inst.Bits(20, 12) != 0b_1110_0111_1001)
{
return(null);
}
var reg_n = inst.Bits(16, 4);
var reg_t = inst.Bits(12, 4);
var reg_m = inst.Bits(0, 4);
return(reg_t, reg_n, reg_m);
}
private (uint reg_t, uint reg_n, uint simm)? getLdr64ImmOffset(uint inst)
{
if (inst.Bits(22, 10) != 0b_11_1110_0101)
{
return(null);
}
var imm = inst.Bits(10, 12);
var reg_t = inst.Bits(0, 5);
var reg_n = inst.Bits(5, 5);
return(reg_t, reg_n, imm);
}
// ARMv7-A Architecture Reference Manual: https://static.docs.arm.com/ddi0406/c/DDI0406C_C_arm_architecture_reference_manual.pdf
// Section A8.8.7, page A8-312 (ADD encoding A1)
private (uint reg_d, uint reg_n, uint reg_m)? getAddReg(uint inst)
{
if (inst.Bits(21, 11) != 0b_1110_0000_100)
{
return(null);
}
var reg_d = inst.Bits(12, 4);
var reg_n = inst.Bits(16, 4);
var reg_m = inst.Bits(0, 4);
return(reg_d, reg_n, reg_m);
}
private (uint reg_n, uint reg_d, uint imm)? getAdd64(uint inst)
{
if (inst.Bits(22, 10) != 0b_1001_0001_00)
{
return(null);
}
var imm = inst.Bits(10, 12);
var reg_n = inst.Bits(5, 5);
var reg_d = inst.Bits(0, 5);
return(reg_n, reg_d, imm);
}
private (uint reg, ulong page)? getAdrp(uint inst, ulong pc)
{
if ((inst.Bits(24, 8) & 0b_1000_1111) != 1 << 7)
{
return(null);
}
var addendLo = inst.Bits(29, 2);
var addendHi = inst.Bits(5, 19);
var addend = (addendHi << 14) + (addendLo << 12);
var page = pc & ~((1Lu << 12) - 1);
var reg = inst.Bits(0, 5);
return(reg, page + addend);
}
// Thumb 2 Supplement Reference Manual: http://class.ece.iastate.edu/cpre288/resources/docs/Thumb-2SupplementReferenceManual.pdf
// Section 3.1
private uint getNextThumbInstruction(IFileFormatReader image)
{
// Assume 16-bit
uint inst = image.ReadUInt16();
// Is 32-bit?
if (inst.Bits(13, 15) == 0b111)
{
if (inst.Bits(11, 2) != 0b00)
{
inst = (inst << 16) + image.ReadUInt16();
}
}
return(inst);
}
// https://static.docs.arm.com/100878/0100/fundamentals_of_armv8_a_100878_0100_en.pdf states:
// Unlike ARMv7-A, there is no implied offset of 4 or 8 bytes
private (uint reg, ulong addr)? getAdr(uint inst, ulong pc)
{
if (inst.Bits(24, 5) != 0b10000 || inst.Bits(31, 1) != 0)
{
return(null);
}
ulong imm = (inst.Bits(5, 19) << 2) + inst.Bits(29, 2);
// Sign extend the 21-bit number to 64 bits
imm = (imm & (1 << 20)) == 0 ? imm : imm | unchecked ((ulong)-(1 << 21));
var reg = inst.Bits(0, 5);
return(reg, pc + imm);
}
// Section A8.8.18, page A8-334 (B encoding A1) private bool isB(uint inst) => inst.Bits(24, 8) == 0b_1110_1010;
public void BitEnumerateUInt32Test(uint num, int[] expected)
{
num.Bits().Should().Equal(expected);
}
private bool isB(uint inst) => inst.Bits(26, 6) == 0b_000101;
public static uint NormalisedBits(this uint value, int firstIndex, int lastIndex)
{
var lsb = Math.Min(firstIndex, lastIndex);
return(value.Bits(firstIndex, lastIndex) >> lsb);
}
