//Add with carry
void adc(CPU *c, OP_CODE_INFO *o){
int8_t carry = getFlag(c,C);
int8_t accum = getRegByte(c,ACCUM);
int8_t operand = o->operand;
int16_t sum = (0x00FF&carry) + (0x00FF&accum) + (0x00FF&operand);
int8_t sumByte = sum & 0x00FF;
setZero(c,sumByte);
if(getFlag(c,D)){ //in decimal mode
//if lower 4 bits of operands plus
//the carry in are larger than 9,
//then we need to apply conversions
//to remain in binary coded decimal format.
if((accum & 0xF) + (operand & 0xF)
+ carry > 9){
sum += 6;
}
setSign(c,sum&0xFF);
setOverflow(c,accum,operand,sum&0xFF);
//if the higher bits aren't in
//BCD format we need to add 96 to convert.
//Black magic from http://nesdev.com/6502.txt
sum += sum > 0x99 ? 96 : 0;
setCarryBCD(c, sum);
} else {
setSign(c,sumByte);
setOverflow(c,accum,operand,sumByte);
setCarry(c,sum);
}
setRegByte(c,ACCUM,sum&0xFF);
}
//Arithmetic shift left
void asl(CPU *c, OP_CODE_INFO *o){
int8_t operand = o->operand;
int16_t res = (0x00FF&operand) << 1;
int8_t resByte = res & 0x00FF;
setCarry(c,res);
setSign(c,resByte);
setZero(c,resByte);
if(o->mode == modeAccumulator){
setRegByte(c,ACCUM,res);
} else {
write(c,o->address,res);
}
}
void simulateToRead()
{
if (_debug)
printf("%*s% 7.2lf ", _indent*8, "", _tNextStop/(400.0*256.0));
int pc = _pch | _memory[2];
int op = _program->op(pc);
incrementPC();
UInt16 r;
if ((op & 0x800) == 0) {
_f = op & 0x1f;
if ((op & 0x400) == 0) {
bool d = ((op & 0x20) != 0); // true if destination is f, false if destination is W
char dc = d ? 'f' : 'W';
switch (op >> 6) {
case 0x0:
if (!d)
switch (_f) {
case 0:
if (_debug) { printf("NOP "); printf("\n"); }
_f = -1;
break;
case 2:
if (_debug) { printf("OPTION "); printf("\n"); }
_f = -1;
_option = _w;
break;
case 3:
if (_debug) { printf("SLEEP "); printf("\n"); }
_f = -1;
throw Exception(String("SLEEP not supported"));
break;
case 4:
if (_debug) { printf("CLRWDT "); printf("\n"); }
_f = -1;
throw Exception(String("CLRWDT not supported"));
break;
case 6:
if (_debug) { printf("TRIS GPIO "); printf("\n"); }
_f = 0x20;
_data = _w;
break;
default:
unrecognizedOpcode(op);
break;
}
else {
if (_debug) { printf("MOVWF 0x%02x ", _f); printf("\n"); }
_data = _w;
}
break;
case 0x1:
if (_debug) {
if (!d)
printf("CLRW ");
else
printf("CLRF 0x%02x ", _f);
printf("\n");
}
storeZ(0, d);
break;
case 0x2:
if (_debug) { printf("SUBWF 0x%02x, %c ", _f, dc); printf("\n"); }
{
UInt8 m = readMemory(_f);
r = m - _w;
if (r & 0x100)
_memory[3] |= 1;
else
_memory[3] &= 0xfe;
if ((m & 0xf) - (_w & 0xf) != (r & 0xf))
_memory[3] |= 2;
else
_memory[3] &= 0xfd;
storeZ(r, d);
}
break;
case 0x3:
if (_debug) { printf("DECF 0x%02x, %c ", _f, dc); printf("\n"); }
storeZ(readMemory(_f) - 1, d);
break;
case 0x4:
if (_debug) { printf("IORWF 0x%02x, %c ", _f, dc); printf("\n"); }
storeZ(readMemory(_f) | _w, d);
break;
case 0x5:
if (_debug) { printf("ANDWF 0x%02x, %c ", _f, dc); printf("\n"); }
storeZ(readMemory(_f) & _w, d);
break;
case 0x6:
if (_debug) { printf("XORWF 0x%02x, %c ", _f, dc); printf("\n"); }
storeZ(readMemory(_f) ^ _w, d);
break;
case 0x7:
if (_debug) { printf("ADDWF 0x%02x, %c ", _f, dc); printf("\n"); }
{
UInt8 m = readMemory(_f);
r = m + _w;
if (r & 0x100)
_memory[3] |= 1;
else
_memory[3] &= 0xfe;
if ((_w & 0xf) + (m & 0xf) != (r & 0xf))
_memory[3] |= 2;
else
_memory[3] &= 0xfd;
storeZ(r, d);
}
break;
case 0x8:
if (_debug) { printf("MOVF 0x%02x, %c ", _f, dc); printf("\n"); }
storeZ(readMemory(_f), d);
break;
case 0x9:
if (_debug) { printf("COMF 0x%02x, %c ", _f, dc); printf("\n"); }
storeZ(~readMemory(_f), d);
break;
case 0xa:
if (_debug) { printf("INCF 0x%02x, %c ", _f, dc); printf("\n"); }
storeZ(readMemory(_f) + 1, d);
break;
case 0xb:
if (_debug) { printf("DECFSZ 0x%02x, %c ", _f, dc); printf("\n"); }
r = readMemory(_f) - 1;
store(r, d);
if (r == 0) {
incrementPC();
_skipping = true;
}
break;
case 0xc:
if (_debug) { printf("RRF 0x%02x, %c ", _f, dc); printf("\n"); }
r = readMemory(_f) | ((_memory[3] & 1) << 8);
setCarry((r & 1) != 0);
store(r >> 1, d);
break;
case 0xd:
if (_debug) { printf("RLF 0x%02x, %c ", _f, dc); printf("\n"); }
r = (readMemory(_f) << 1) | (_memory[3] & 1);
setCarry((r & 0x100) != 0);
store(r, d);
break;
case 0xe:
if (_debug) { printf("SWAPF 0x%02x, %c ", _f, dc); printf("\n"); }
r = readMemory(_f);
store((r >> 4) | (r << 4), d);
break;
case 0xf:
if (_debug) { printf("INCFSF 0x%02x, %c ", _f, dc); printf("\n"); }
r = readMemory(_f) + 1;
store(r, d);
if (r == 0) {
incrementPC();
_skipping = true;
}
break;
}
}
