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bool ARM::condition(uint4 condition) {
switch(condition) {
case 0: return cpsr().z == 1; //EQ (equal)
case 1: return cpsr().z == 0; //NE (not equal)
case 2: return cpsr().c == 1; //CS (carry set)
case 3: return cpsr().c == 0; //CC (carry clear)
case 4: return cpsr().n == 1; //MI (negative)
case 5: return cpsr().n == 0; //PL (positive)
case 6: return cpsr().v == 1; //VS (overflow)
case 7: return cpsr().v == 0; //VC (no overflow)
case 8: return cpsr().c == 1 && cpsr().z == 0; //HI (unsigned higher)
case 9: return cpsr().c == 0 || cpsr().z == 1; //LS (unsigned lower or same)
case 10: return cpsr().n == cpsr().v; //GE (signed greater than or equal)
case 11: return cpsr().n != cpsr().v; //LT (signed less than)
case 12: return cpsr().z == 0 && cpsr().n == cpsr().v; //GT (signed greater than)
case 13: return cpsr().z == 1 || cpsr().n != cpsr().v; //LE (signed less than or equal)
case 14: return true; //AL (always)
case 15: return false; //NV (never)
}
}
uint32 ARM::bit(uint32 result) {
if(cpsr().t || instruction() & (1 << 20)) {
cpsr().n = result >> 31;
cpsr().z = result == 0;
cpsr().c = carryout();
}
return result;
}
uint32 ARM::add(uint32 source, uint32 modify, bool carry) {
uint32 result = source + modify + carry;
if(cpsr().t || instruction() & (1 << 20)) {
uint32 overflow = ~(source ^ modify) & (source ^ result);
cpsr().n = result >> 31;
cpsr().z = result == 0;
cpsr().c = (1u << 31) & (overflow ^ source ^ modify ^ result);
cpsr().v = (1u << 31) & (overflow);
}
return result;
}
uint32 ARM::sub(uint32 source, uint32 modify, bool carry) {
return add(source, ~modify, carry);
}
uint32 ARM::mul(uint32 product, uint32 multiplicand, uint32 multiplier) {
product += multiplicand * multiplier;
if(cpsr().t || instruction() & (1 << 20)) {
cpsr().n = product >> 31;
cpsr().z = product == 0;
}
return product;
}
uint32 ARM::lsl(uint32 source, uint8 shift) {
carryout() = cpsr().c;
if(shift == 0) return source;
carryout() = shift > 32 ? 0 : source & (1 << 32 - shift);
source = shift > 31 ? 0 : source << shift;
return source;
}
uint32 ARM::lsr(uint32 source, uint8 shift) {
carryout() = cpsr().c;
if(shift == 0) return source;
carryout() = shift > 32 ? 0 : source & (1 << shift - 1);
source = shift > 31 ? 0 : source >> shift;
return source;
}
uint32 ARM::asr(uint32 source, uint8 shift) {
carryout() = cpsr().c;
if(shift == 0) return source;
carryout() = shift > 32 ? source & (1 << 31) : source & (1 << shift - 1);
source = shift > 31 ? (int32)source >> 31 : (int32)source >> shift;
return source;
}
uint32 ARM::ror(uint32 source, uint8 shift) {
carryout() = cpsr().c;
if(shift == 0) return source;
if(shift &= 31)
source = source << 32 - shift | source >> shift;
carryout() = source & (1 << 31);
return source;
}
uint32 ARM::rrx(uint32 source) {
carryout() = source & 1;
return (cpsr().c << 31) | (source >> 1);
}
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