// ReSharper disable once UnusedMember.Global
public void Run(int count)
{
var memory = Memory;
var REGS = new int[RegisterIndex.CPSR + 1];
Regs.Load(REGS);
var q = (REGS[RegisterIndex.CPSR] & FQ) != 0;
var v = (REGS[RegisterIndex.CPSR] & FV) != 0;
var c = (REGS[RegisterIndex.CPSR] & FC) != 0;
var z = (REGS[RegisterIndex.CPSR] & FZ) != 0;
var n = (REGS[RegisterIndex.CPSR] & FN) != 0;
Debug.Assert((REGS[RegisterIndex.PC] & I0) == 0);
REGS[RegisterIndex.PC] &= ~I0;
try
{
while (count-- > 0)
{
var incr_pc = true;
int Rs, Rd, Rb;
int left, right, value, addr;
ulong lvalue;
uint uleft, uvalue;
bool L, B, S, H;
int list;
var code = memory.ReadShort(REGS[RegisterIndex.PC]);
switch ((code >> 12) & L4)
{
case 0b0000:
case 0b0001: // :000x
Rs = (code >> 3) & L3;
Rd = code & L3;
left = REGS[Rs];
switch ((code >> 11) & L2)
{
// Format 1: move shifted register
case 0: // :00000
// LSL Rd, Rs, #Offset5
right = (code >> 6) & L5; // right = 0 ~ 31
uleft = (uint)left;
uvalue = uleft << right;
value = (int)uvalue;
if (right > 0)
{
c = ((uleft << (right - 1)) & FN) != 0;
}
break;
case 1: // :00001
// LSR Rd, Rs, #Offset5
right = (code >> 6) & L5; // right = 1 ~ 32
if (right == 0)
{
value = 0;
c = (left & FN) != 0;
}
else
{
uleft = (uint)left;
uvalue = uleft >> right;
value = (int)uvalue;
c = (left & (1 << (right - 1))) != 0;
}
break;
case 2: // :00010
// ASR Rd, Rs, #Offset5
right = (code >> 6) & L5; // right = 1 ~ 32
if (right == 0)
{
value = left >> 31 >> 1;
c = (left & FN) != 0;
}
else
{
value = left >> right;
c = (left & (1 << (right - 1))) != 0;
}
break;
case 3: // :00011
// Format 2: add/subtract
var I = ((code >> 10) & 0b1) != 0;
var Rn = (code >> 6) & L3;
Rs = (code >> 3) & L3;
Rd = code & L3;
left = REGS[Rs];
right = I ? Rn : REGS[Rn];
switch ((code >> 9) & L1)
{
case 0: // :0001100 | :0001110
// ADD Rd, Rs, Rn
// ADD Rd, Rs, #Offset3
lvalue = Add(left, right);
value = (int)lvalue;
SetC(lvalue);
SetV_Add(value, left, right);
break;
case 1: // :0001101 | :0001111
// SUB Rd, Rs, Rn
// SUB Rd, Rs, #Offset3
lvalue = Sub(left, right);
value = (int)lvalue;
SetC(lvalue);
SetV_Sub(value, left, right);
break;
default:
throw new UnexceptedLogic();
}
break;
default:
throw new UnexceptedLogic();
}
SetNZ(value);
REGS[Rd] = value;
break;
case 0b0010:
case 0b0011: // :001
// Format 3: move/compare/add/subtract immediate
Rd = (code >> 8) & L3;
left = REGS[Rd];
right = code & L8;
switch ((code >> 11) & L2)
{
case 0: // :001100
// MOV Rd, #Offset8
value = right;
REGS[Rd] = value;
break;
case 1: // :001101
// CMP Rd, #Offset8
lvalue = Sub(left, right);
value = (int)lvalue;
// only compare (no write)
SetC(lvalue);
SetV_Sub(value, left, right);
break;
case 2: // :001110
// ADD Rd, #Offset8
lvalue = Add(left, right);
value = (int)lvalue;
REGS[Rd] = value;
SetC(lvalue);
SetV_Add(value, left, right);
break;
case 3: // :001111
// SUB Rd, #Offset8
lvalue = Sub(left, right);
value = (int)lvalue;
REGS[Rd] = value;
SetC(lvalue);
SetV_Sub(value, left, right);
break;
default:
throw new UnexceptedLogic();
}
SetNZ(value);
break;
case 0b0100: // :0100
switch ((code >> 10) & L2)
{
case 0b00: // :010000
// Format 4: ALU operations
Rs = (code >> 3) & L3;
Rd = code & L3;
left = REGS[Rd];
right = REGS[Rs];
switch ((code >> 6) & L4)
{
case 0b0000: // :0100000000
// AND Rd, Rs
// Rd:= Rd AND Rs
value = left & right;
REGS[Rd] = value;
break;
case 0b0001: // :0100000001
// EOR Rd, Rs
// Rd:= Rd EOR Rs
value = left ^ right;
REGS[Rd] = value;
break;
case 0b0010: // :0100000010
// LSL Rd, Rs
// Rd := Rd << Rs
if (right >= 32)
{
value = 0;
c = right == 32 && (left & 1) != 0;
}
else if (right < 0)
{
value = 0;
c = false;
}
else if (right == 0)
{
value = left;
}
else
{
uleft = (uint)left;
uvalue = uleft << right;
value = (int)uvalue;
c = ((uleft << (right - 1)) & FN) != 0;
}
REGS[Rd] = value;
break;
case 0b0011: // :0100000011
// LSR Rd, Rs
// Rd := Rd >> Rs
if (right >= 32)
{
value = 0;
c = right == 32 && (left & FN) != 0;
}
else if (right < 0)
{
value = 0;
c = false;
}
else if (right == 0)
{
value = left;
}
else
{
uleft = (uint)left;
uvalue = uleft >> right;
value = (int)uvalue;
REGS[Rd] = value;
c = ((uleft >> (right - 1)) & 1) != 0;
}
break;
case 0b0100: // :0100000100
// ASR Rd, Rs
// Rd := Rd ASR Rs
if (right < 0 || right >= 32)
{
value = left > 0? 0: -1;
c = value < 0;
}
else if (right == 0)
{
value = left;
}
else
{
value = left >> right;
REGS[Rd] = value;
c = (left & (1 << (right - 1))) != 0;
}
break;
case 0b0101: // :0100000101
// ADC Rd, Rs
// Rd := Rd + Rs + C-bit
lvalue = Add(left, right) + (c ? 1UL : 0UL);
value = (int)lvalue;
REGS[Rd] = value;
c = lvalue != (uint)value;
v = left > 0 && right > 0 && value < 0 ||
left < 0 && right < 0 && value > 0;
break;
case 0b0110: // :0100000110
// SBC Rd, Rs
// Rd := Rd - Rs - NOT C-bit
var signed = (long)left - right - (c ? 0L : 1L);
value = left - right - (c ? 0 : 1);
REGS[Rd] = value;
c = c || value < 0;
v = signed != value;
break;
case 0b0111: // :0100000111
// ROR Rd, Rs
// Rd := Rd ROR Rs
uleft = (uint)left;
right &= 31;
value = (int)((uleft >> right) |
(uleft << (32 - right)));
c = ((uleft >> (right - 1)) & I0) != 0;
REGS[Rd] = value;
break;
case 0b1000: // :0100001000
// TST Rd, Rs
// Set condition codes on Rd AND Rs
value = left & right;
// only compare (no write)
break;
case 0b1001: // :0100001001
// NEG Rd, Rs
// Rd = -Rs
lvalue = Sub(0, right);
value = (int)lvalue;
REGS[Rd] = value;
SetC(lvalue);
SetV_Sub(value, 0, right);
break;
case 0b1010: // :0100001010
// CMP Rd, Rs
// Set condition codes on Rd - Rs
lvalue = Sub(left, right);
value = (int)lvalue;
// only compare (no write)
SetC(lvalue);
SetV_Sub(value, left, right);
break;
case 0b1011: // :0100001011
// CMN Rd, Rs
// Set condition codes on Rd + Rs
lvalue = Add(left, right);
value = (int)lvalue;
// only compare (no write)
SetC(lvalue);
SetV_Add(value, left, right);
break;
case 0b1100: // :0100001100
// ORR Rd, Rs
// Rd := Rd OR Rs
value = left | right;
REGS[Rd] = value;
break;
case 0b1101: // :0100001101
// MUL Rd, Rs
// Rd := Rs * Rd
long svalue = left * right;
value = (int)svalue;
REGS[Rd] = value;
c |= value != svalue;
v = false;
// v = ((a ^ val) & ((~ b + 1) ^ val) & I31) != 0;
break;
case 0b1110: // :0100001110
// BIC Rd, Rs
// Rd := Rd AND NOT Rs
value = left & ~right;
REGS[Rd] = value;
break;
case 0b1111: // :0100001111
// MVN Rd, Rs
// Rd := NOT Rs
value = ~right;
REGS[Rd] = value;
break;
default:
throw new UnexceptedLogic();
}
SetNZ(value);
break;
case 0b01: // :010001
// Format 5: Hi register operations/branch exchange
var H1 = ((code >> 7) & L1) != 0;
var H2 = ((code >> 6) & L1) != 0;
Rd = (code & L3) + (H1 ? 8 : 0);
Rs = ((code >> 3) & L3) + (H2 ? 8 : 0);
switch ((code >> 8) & L2)
{
case 0b00: // :01000100
// ADD Rd, Hs
// ADD Hd, Rs
// ADD Hd, Hs
left = REGS[Rd];
right = REGS[Rs];
if (Rs == RegisterIndex.PC)
{
right += 4;
}
REGS[Rd] = left + right;
// no write condition code flags
break;
case 0b01: // :01000101
// CMP Rd, Hs
// CMP Hd, Rs
// CMP Hd, Hs
left = REGS[Rd];
right = REGS[Rs];
lvalue = Sub(left, right);
value = (int)lvalue;
// only compare (no write)
SetNZ(value);
SetC(lvalue);
SetV_Sub(value, left, right);
break;
case 0b10: // :01000110
// MOV Rd, Hs
// MOV Hd, Rs
// MOV Hd, Hs
value = REGS[Rs];
if (Rd == RegisterIndex.PC)
{
value -= 2;
}
REGS[Rd] = value;
break;
case 0b11: // :01000111
// BX Rs
// BX Hs
value = REGS[Rs];
if ((value & I0) != 1)
{
throw new UnknownInstructionException();
}
if (H1)
{
REGS[RegisterIndex.LR] = (REGS[RegisterIndex.PC] + 2) | I0;
}
REGS[RegisterIndex.PC] = value & ~I0;
incr_pc = false;
break;
default:
throw new UnexceptedLogic();
}
break;
case 0b10:
case 0b11: // :01001
// Format 6: PC-relative load
// LDR Rd, [PC, #Imm]
Rd = (code >> 8) & L3;
addr = (code & L8) << 2;
addr += (REGS[RegisterIndex.PC] + 4) & ~I1;
REGS[Rd] = memory.ReadInt(addr);
break;
}
break;
case 0b0101: // :0101
int Ro;
if ((code & I9) == 0) // :0101xx0
{
// Format 7: load/store with register offset
L = (code & I11) != 0;
B = (code & I10) != 0;
Ro = (code >> 6) & L3;
Rb = (code >> 3) & L3;
Rd = code & L3;
addr = REGS[Rb] + REGS[Ro];
if (L)
{
if (B) // :0101110
{
// LDRB Rd, [Rb, Ro]
REGS[Rd] = memory.ReadByte(addr);
}
else // :0101100
{
// LDR Rd, [Rb, Ro]
REGS[Rd] = memory.ReadInt(addr);
}
}
else
{
if (B) // :0101010
{
// STRB Rd, [Rb, Ro]
memory.WriteByte(addr, (byte)REGS[Rd]);
}
else // :0101000
{
// STR Rd, [Rb, Ro]
memory.WriteInt(addr, REGS[Rd]);
}
}
}
else // :0101xx1
{
// Format 8: load/store sign-extended byte/halfword
H = (code & I11) != 0;
S = (code & I10) != 0;
Ro = (code >> 6) & L3;
Rb = (code >> 3) & L3;
Rd = code & L3;
addr = REGS[Rb] + REGS[Ro];
if (S)
{
if (H) // :0101111
{
// LDSH Rd, [Rb, Ro]
value = (short)memory.ReadShort(addr);
}
else // :0101011
{
// LDSB Rd, [Rb, Ro]
value = (sbyte)memory.ReadByte(addr);
}
REGS[Rd] = value;
}
else
{
if (H) // :0101101
{
// LDRH Rd, [Rb, Ro]
value = memory.ReadShort(addr);
REGS[Rd] = value;
}
else // :0101001
{
// STRH Rd, [Rb, Ro]
value = REGS[Rd];
memory.WriteShort(addr, (ushort)value);
}
}
}
break;
case 0b0110:
case 0b0111: // :011
// Format 9: load/store with immediate offset
B = (code & I12) != 0;
L = (code & I11) != 0;
Rb = (code >> 3) & L3;
Rd = code & L3;
value = (code >> 6) & L5;
if (!B)
{
value <<= 2;
}
addr = REGS[Rb] + value;
if (L)
{
// ReSharper disable once ConvertIfStatementToConditionalTernaryExpression
if (!B) // :01111
// LDR Rd, [Rb, #Imm]
{
value = memory.ReadInt(addr);
}
else // :01101
// LDRB Rd, [Rb, #Imm]
{
value = memory.ReadByte(addr);
}
REGS[Rd] = value;
}
else
{
value = REGS[Rd];
if (!B) // :01100
// STR Rd, [Rb, #Imm]
{
memory.WriteInt(addr, value);
}
else // :01110
// STRB Rd, [Rb, #Imm]
{
memory.WriteByte(addr, (byte)value);
}
}
break;
case 0b1000: // :1000x
// Format 10: load/store halfword
L = (code & I11) != 0;
Rb = (code >> 3) & L3;
Rd = code & L3;
value = ((code >> 6) & L5) << 1;
addr = REGS[Rb] + value;
if (L) // :10001
// LDRH Rd, [Rb, #Imm]
{
REGS[Rd] = memory.ReadShort(addr);
}
else // :10000
// STRH Rd, [Rb, #Imm]
{
memory.WriteShort(addr, (ushort)REGS[Rd]);
}
break;
case 0b1001: // :1001x
// Format 11: SP-relative load/store
L = (code & I11) != 0;
Rd = (code >> 8) & L3;
value = (code & L8) << 2;
addr = REGS[RegisterIndex.SP] + value;
if (L) // LDR:10011
// LDR Rd, [SP, #Imm]
{
REGS[Rd] = memory.ReadInt(addr);
}
else // STR:10010
// STR Rd, [SP, #Imm]
{
memory.WriteInt(addr, REGS[Rd]);
}
break;
case 0b1010: // :1010x
// Format 12: load address
var fSP = (code & I11) != 0;
Rd = (code >> 8) & L3;
value = (code & L8) << 2;
if (fSP) // :10101
// ADD Rd, SP, #Imm
{
value += REGS[RegisterIndex.SP];
}
else // :10100
// ADD Rd, PC, #Imm
{
value += (REGS[RegisterIndex.PC] + 4) & ~I1;
}
REGS[Rd] = value;
// CPSR condition codes are unaffected
break;
case 0b1011: // :1011
bool R;
switch ((code >> 8) & L4)
{
case 0b0000: // :10110000x
// Format 13: add offset to Stack Pointer
S = (code & I7) != 0;
value = (code & L7) << 2;
if (S) // :101100000
// ADD SP, #-Imm
{
REGS[RegisterIndex.SP] -= value;
}
else // :101100001
// ADD SP, #Imm
{
REGS[RegisterIndex.SP] += value;
}
// condition codes are not set
break;
case 0b0001: // :10110001
// CBZ Rd, #Imm
throw new NotImplementedException();
case 0b0010: // :10110010
// SXTH, SXTB, UXTH, UXTB
Rs = (code >> 3) & L3;
Rd = code & L3;
value = REGS[Rs];
switch ((code >> 6) & L2)
{
case 0b00: // :1011001000
// SXTH Rd, Rs
value = (short)value;
break;
case 0b01: // :1011001001
// SXTB Rd, Rs
value = (sbyte)value;
break;
case 0b10: // :1011001010
// UXTH Rd, Rs
value = (ushort)value;
break;
case 0b11: // :1011001011
// UXTB Rd, Rs
value = (byte)value;
break;
default:
throw new UnexceptedLogic();
}
REGS[Rd] = value;
break;
case 0b0011: // :10110011
// CBZ Rd, #Imm
throw new NotImplementedException();
case 0b0100:
case 0b0101: // :1011010x
// Format 14: push/pop registers
R = (code & I8) != 0;
list = code & L8;
addr = REGS[RegisterIndex.SP];
try
{
if (R) // :10110101
{
// PUSH { ..., LR }
addr -= 4;
memory.WriteInt(addr, REGS[RegisterIndex.LR]);
}
// PUSH { Rlist }
for (var i = 7; i >= 0; i--)
{
if ((list & (1 << i)) != 0)
{
addr -= 4;
memory.WriteInt(addr, REGS[i]);
}
}
}
finally
{
REGS[RegisterIndex.SP] = addr;
}
break;
case 0b0110: // :10110110
case 0b0111: // :10110111
case 0b1000: // :10111000
throw new UnknownInstructionException();
case 0b1001: // :10111001
// CBNZ Rd, #Imm
throw new NotImplementedException();
case 0b1010: // :10111010xx
Rs = (code >> 3) & L3;
Rd = code & L3;
value = REGS[Rs];
switch ((code >> 6) & L2)
{
case 0b00: // :1011101000
// REV Rd, Rs
value = ((value >> 24) & 0xFF) |
((value >> 16) & 0xFF) << 8 |
((value >> 8) & 0xFF) << 16 |
((value & 0xFF) << 24);
break;
case 0b01: // :1011101001
// REV16 Rd, Rs
throw new NotImplementedException();
case 0b10: // :1011101010
// INVALID
throw new UnknownInstructionException();
case 0b11: // :1011101011
// REVSH Rd, Rs
throw new NotImplementedException();
default:
throw new UnexceptedLogic();
}
REGS[Rd] = value;
break;
case 0b1011: // :10111011
// CBNZ Rd, #Imm
throw new NotImplementedException();
case 0b1100:
case 0b1101: // :1011110x
// Format 14: push/pop registers
R = (code & I8) != 0;
list = code & L8;
addr = REGS[RegisterIndex.SP];
try
{
// POP { Rlist }
for (var i = 0; i < 8; i++)
{
if ((list & (1 << i)) != 0)
{
REGS[i] = memory.ReadInt(addr);
addr += 4;
}
}
if (R) // :10111101 {..., PC}
{
// POP { ..., PC }
value = memory.ReadInt(addr);
if ((value & I0) != 1)
{
throw new InvalidAddressArmException();
}
REGS[RegisterIndex.PC] = value & ~I0;
addr += 4;
incr_pc = false;
}
}
finally
{
REGS[RegisterIndex.SP] = addr;
}
break;
case 0b1110: // :10111110
case 0b1111: // :10111111
throw new UnknownInstructionException();
default:
throw new UnexceptedLogic();
}
break;
case 0b1100: // :1100
// Format 15: multiple load/store
L = (code & I11) != 0;
list = code & L8;
Rb = (code >> 8) & L3;
addr = REGS[Rb];
try
{
if (!L) // :11001
{
// STMIA Rb!, { Rlist }
for (var i = 0; i < 8; i++)
{
if ((list & (1 << i)) != 0)
{
memory.WriteInt(addr, REGS[i]);
addr += 4;
}
}
}
else // :11000
{
// LDMIA Rb!, { Rlist }
for (var i = 0; i < 8; i++)
{
if ((list & (1 << i)) != 0)
{
REGS[i] = memory.ReadInt(addr);
addr += 4;
}
}
}
}
finally
{
REGS[Rb] = addr;
}
break;
case 0b1101: // :1101
var soffset = (byte)(code & L8);
var cond = false;
// Format 16: conditional branch
switch ((code >> 8) & L4)
{
case 0b0000: // :11010000
// BEQ label
cond = z;
break;
case 0b0001: // :11010001
// BNE label
cond = !z;
break;
case 0b0010: // :11010010
// BCS label
cond = c;
break;
case 0b0011: // :11010011
// BCC label
cond = !c;
break;
case 0b0100: // :11010100
// BMI label
cond = n;
break;
case 0b0101: // :11010101
// BPL label
cond = !n;
break;
case 0b0110: // :11010110
// BVS label
cond = v;
break;
case 0b0111: // :11010111
// BVC label
cond = !v;
break;
case 0b1000: // :11011000
// BHI label
cond = c && !z;
break;
case 0b1001: // :11011001
// BLS label
cond = !c || z;
break;
case 0b1010: // :11011010
// BGE label
cond = !(n ^ v);
// = (n && v) || (!n && !v)
break;
case 0b1011: // :11011011
// BLT label
cond = n ^ v;
// = (n && !v) || (!n && v)
break;
case 0b1100: // :11011100
// BGT label
cond = !z && !(n ^ v);
// = !z && (n && v || !n && !v)
break;
case 0b1101: // :11011101
// BLE label
cond = z || n ^ v;
// = z || (n && !v) || (!n && v)
break;
case 0b1110: // :11011110
throw new UnknownInstructionException();
case 0b1111: // :11011111
// Format 17: software interrupt
// SWI Value8
Interrupt(soffset);
break;
}
if (cond)
{
value = (soffset & L8) << 1;
if ((value & I8) != 0)
{
value |= -1 ^ L8;
}
REGS[RegisterIndex.PC] += 4 + value;
incr_pc = false;
}
break;
case 0b1110: // :11100
// Format 18: unconditional branch
if ((code & I11) != 0)
{
throw new UnknownInstructionException();
}
value = (code & L10) << 1;
if ((code & I10) != 0)
{
value |= -1 ^ L11;
}
REGS[RegisterIndex.PC] += 4 + value;
incr_pc = false;
break;
case 0b1111: // :1111
// Format 19: long branch with link
H = ((code >> 11) & L1) != 0;
value = code & L11;
if (!H)
{
REGS[RegisterIndex.LR] = value << 12;
count++;
}
else
{
addr = REGS[RegisterIndex.LR];
addr |= value << 1;
if ((addr & (1 << 22)) != 0)
{
addr <<= 9;
addr >>= 9;
}
var lr = REGS[RegisterIndex.PC];
REGS[RegisterIndex.PC] = lr + addr + 2;
REGS[RegisterIndex.LR] = lr + 3;
incr_pc = false;
}
break;
default:
throw new UnknownInstructionException();
}
if (incr_pc)
{
REGS[RegisterIndex.PC] += 2;
}
}
}
finally
{
REGS[RegisterIndex.CPSR] = (q ? FQ : 0) |
(v ? FV : 0) |
(c ? FC : 0) |
(z ? FZ : 0) |
(n ? FN : 0);
Regs.Store(REGS);
}
ulong Add(int a, int b)
=> (ulong)(uint)a + (uint)b;
ulong Sub(int a, int b)
=> (ulong)(uint)a + ~(uint)b + 1;
void SetNZ(int val)
{
n = val < 0;
z = val == 0;
}
void SetC(ulong lval)
=> c = lval > uint.MaxValue;
void SetV_Add(int val, int a, int b)
=> v = ((a ^ val) & (b ^ val) & FN) != 0;
void SetV_Sub(int val, int a, int b)
=> SetV_Add(val, a, ~b + 1);
}