/
8080emu.c
2159 lines (2118 loc) · 76.1 KB
/
8080emu.c
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#include <stdio.h>
#include <stdlib.h>
#include <inttypes.h>
#include "8080emu.h"
/*
code is a valid pointer to 8080 assembly code
pc is the current offset into the code
returns the number of bytes of the op
*/
int disassemble8080Op(unsigned char *code, int pc) {
int opbytes = 1;
printf ("%04x ", pc);
switch (*code) {
case 0x00: printf("NOP"); break;
case 0x01: printf("LXI B,#$%02x%02x", code[2], code[1]); opbytes=3; break;
case 0x02: printf("STAX B"); break;
case 0x03: printf("INX B"); break;
case 0x04: printf("INR B"); break;
case 0x05: printf("DCR B"); break;
case 0x06: printf("MVI B,#$%02x", code[1]); opbytes=2; break;
case 0x07: printf("RLC"); break;
case 0x08: printf("NOP"); break;
case 0x09: printf("DAD B"); break;
case 0x0a: printf("LDAX B"); break;
case 0x0b: printf("DCX B"); break;
case 0x0c: printf("INR C"); break;
case 0x0d: printf("DCR C"); break;
case 0x0e: printf("MVI C,#$%02x", code[1]); opbytes = 2; break;
case 0x0f: printf("RRC"); break;
case 0x10: printf("NOP"); break;
case 0x11: printf("LXI D,#$%02x%02x", code[2], code[1]); opbytes=3; break;
case 0x12: printf("STAX D"); break;
case 0x13: printf("INX D"); break;
case 0x14: printf("INR D"); break;
case 0x15: printf("DCR D"); break;
case 0x16: printf("MVI D,#$%02x", code[1]); opbytes=2; break;
case 0x17: printf("RAL"); break;
case 0x18: printf("NOP"); break;
case 0x19: printf("DAD D"); break;
case 0x1a: printf("LDAX D"); break;
case 0x1b: printf("DCX D"); break;
case 0x1c: printf("INR E"); break;
case 0x1d: printf("DCR E"); break;
case 0x1e: printf("MVI E,#$%02x", code[1]); opbytes = 2; break;
case 0x1f: printf("RAR"); break;
case 0x20: printf("NOP"); break;
case 0x21: printf("LXI H,#$%02x%02x", code[2], code[1]); opbytes=3; break;
case 0x22: printf("SHLD $%02x%02x", code[2], code[1]); opbytes=3; break;
case 0x23: printf("INX H"); break;
case 0x24: printf("INR H"); break;
case 0x25: printf("DCR H"); break;
case 0x26: printf("MVI H,#$%02x", code[1]); opbytes=2; break;
case 0x27: printf("DAA"); break;
case 0x28: printf("NOP"); break;
case 0x29: printf("DAD H"); break;
case 0x2a: printf("LHLD $%02x%02x", code[2], code[1]); opbytes=3; break;
case 0x2b: printf("DCX H"); break;
case 0x2c: printf("INR L"); break;
case 0x2d: printf("DCR L"); break;
case 0x2e: printf("MVI L,#$%02x", code[1]); opbytes = 2; break;
case 0x2f: printf("CMA"); break;
case 0x30: printf("NOP"); break;
case 0x31: printf("LXI SP,#$%02x%02x", code[2], code[1]); opbytes=3; break;
case 0x32: printf("STA $%02x%02x", code[2], code[1]); opbytes=3; break;
case 0x33: printf("INX SP"); break;
case 0x34: printf("INR M"); break;
case 0x35: printf("DCR M"); break;
case 0x36: printf("MVI M,#$%02x", code[1]); opbytes=2; break;
case 0x37: printf("STC"); break;
case 0x38: printf("NOP"); break;
case 0x39: printf("DAD SP"); break;
case 0x3a: printf("LDA $%02x%02x", code[2], code[1]); opbytes=3; break;
case 0x3b: printf("DCX SP"); break;
case 0x3c: printf("INR A"); break;
case 0x3d: printf("DCR A"); break;
case 0x3e: printf("MVI A,#$%02x", code[1]); opbytes = 2; break;
case 0x3f: printf("CMC"); break;
case 0x40: printf("MOV B,B"); break;
case 0x41: printf("MOV B,C"); break;
case 0x42: printf("MOV B,D"); break;
case 0x43: printf("MOV B,E"); break;
case 0x44: printf("MOV B,H"); break;
case 0x45: printf("MOV B,L"); break;
case 0x46: printf("MOV B,M"); break;
case 0x47: printf("MOV B,A"); break;
case 0x48: printf("MOV C,B"); break;
case 0x49: printf("MOV C,C"); break;
case 0x4a: printf("MOV C,D"); break;
case 0x4b: printf("MOV C,E"); break;
case 0x4c: printf("MOV C,H"); break;
case 0x4d: printf("MOV C,L"); break;
case 0x4e: printf("MOV C,M"); break;
case 0x4f: printf("MOV C,A"); break;
case 0x50: printf("MOV D,B"); break;
case 0x51: printf("MOV D,C"); break;
case 0x52: printf("MOV D,D"); break;
case 0x53: printf("MOV D.E"); break;
case 0x54: printf("MOV D,H"); break;
case 0x55: printf("MOV D,L"); break;
case 0x56: printf("MOV D,M"); break;
case 0x57: printf("MOV D,A"); break;
case 0x58: printf("MOV E,B"); break;
case 0x59: printf("MOV E,C"); break;
case 0x5a: printf("MOV E,D"); break;
case 0x5b: printf("MOV E,E"); break;
case 0x5c: printf("MOV E,H"); break;
case 0x5d: printf("MOV E,L"); break;
case 0x5e: printf("MOV E,M"); break;
case 0x5f: printf("MOV E,A"); break;
case 0x60: printf("MOV H,B"); break;
case 0x61: printf("MOV H,C"); break;
case 0x62: printf("MOV H,D"); break;
case 0x63: printf("MOV H.E"); break;
case 0x64: printf("MOV H,H"); break;
case 0x65: printf("MOV H,L"); break;
case 0x66: printf("MOV H,M"); break;
case 0x67: printf("MOV H,A"); break;
case 0x68: printf("MOV L,B"); break;
case 0x69: printf("MOV L,C"); break;
case 0x6a: printf("MOV L,D"); break;
case 0x6b: printf("MOV L,E"); break;
case 0x6c: printf("MOV L,H"); break;
case 0x6d: printf("MOV L,L"); break;
case 0x6e: printf("MOV L,M"); break;
case 0x6f: printf("MOV L,A"); break;
case 0x70: printf("MOV M,B"); break;
case 0x71: printf("MOV M,C"); break;
case 0x72: printf("MOV M,D"); break;
case 0x73: printf("MOV M.E"); break;
case 0x74: printf("MOV M,H"); break;
case 0x75: printf("MOV M,L"); break;
case 0x76: printf("HLT"); break;
case 0x77: printf("MOV M,A"); break;
case 0x78: printf("MOV A,B"); break;
case 0x79: printf("MOV A,C"); break;
case 0x7a: printf("MOV A,D"); break;
case 0x7b: printf("MOV A,E"); break;
case 0x7c: printf("MOV A,H"); break;
case 0x7d: printf("MOV A,L"); break;
case 0x7e: printf("MOV A,M"); break;
case 0x7f: printf("MOV A,A"); break;
case 0x80: printf("ADD B"); break;
case 0x81: printf("ADD C"); break;
case 0x82: printf("ADD D"); break;
case 0x83: printf("ADD E"); break;
case 0x84: printf("ADD H"); break;
case 0x85: printf("ADD L"); break;
case 0x86: printf("ADD M"); break;
case 0x87: printf("ADD A"); break;
case 0x88: printf("ADC B"); break;
case 0x89: printf("ADC C"); break;
case 0x8a: printf("ADC D"); break;
case 0x8b: printf("ADC E"); break;
case 0x8c: printf("ADC H"); break;
case 0x8d: printf("ADC L"); break;
case 0x8e: printf("ADC M"); break;
case 0x8f: printf("ADC A"); break;
case 0x90: printf("SUB B"); break;
case 0x91: printf("SUB C"); break;
case 0x92: printf("SUB D"); break;
case 0x93: printf("SUB E"); break;
case 0x94: printf("SUB H"); break;
case 0x95: printf("SUB L"); break;
case 0x96: printf("SUB M"); break;
case 0x97: printf("SUB A"); break;
case 0x98: printf("SBB B"); break;
case 0x99: printf("SBB C"); break;
case 0x9a: printf("SBB D"); break;
case 0x9b: printf("SBB E"); break;
case 0x9c: printf("SBB H"); break;
case 0x9d: printf("SBB L"); break;
case 0x9e: printf("SBB M"); break;
case 0x9f: printf("SBB A"); break;
case 0xa0: printf("ANA B"); break;
case 0xa1: printf("ANA C"); break;
case 0xa2: printf("ANA D"); break;
case 0xa3: printf("ANA E"); break;
case 0xa4: printf("ANA H"); break;
case 0xa5: printf("ANA L"); break;
case 0xa6: printf("ANA M"); break;
case 0xa7: printf("ANA A"); break;
case 0xa8: printf("XRA B"); break;
case 0xa9: printf("XRA C"); break;
case 0xaa: printf("XRA D"); break;
case 0xab: printf("XRA E"); break;
case 0xac: printf("XRA H"); break;
case 0xad: printf("XRA L"); break;
case 0xae: printf("XRA M"); break;
case 0xaf: printf("XRA A"); break;
case 0xb0: printf("ORA B"); break;
case 0xb1: printf("ORA C"); break;
case 0xb2: printf("ORA D"); break;
case 0xb3: printf("ORA E"); break;
case 0xb4: printf("ORA H"); break;
case 0xb5: printf("ORA L"); break;
case 0xb6: printf("ORA M"); break;
case 0xb7: printf("ORA A"); break;
case 0xb8: printf("CMP B"); break;
case 0xb9: printf("CMP C"); break;
case 0xba: printf("CMP D"); break;
case 0xbb: printf("CMP E"); break;
case 0xbc: printf("CMP H"); break;
case 0xbd: printf("CMP L"); break;
case 0xbe: printf("CMP M"); break;
case 0xbf: printf("CMP A"); break;
case 0xc0: printf("RNZ"); break;
case 0xc1: printf("POP B"); break;
case 0xc2: printf("JNZ $%02x%02x",code[2],code[1]); opbytes = 3; break;
case 0xc3: printf("JMP $%02x%02x",code[2],code[1]); opbytes = 3; break;
case 0xc4: printf("CNZ $%02x%02x",code[2],code[1]); opbytes = 3; break;
case 0xc5: printf("PUSH B"); break;
case 0xc6: printf("ADI #$%02x",code[1]); opbytes = 2; break;
case 0xc7: printf("RST 0"); break;
case 0xc8: printf("RZ"); break;
case 0xc9: printf("RET"); break;
case 0xca: printf("JZ $%02x%02x",code[2],code[1]); opbytes = 3; break;
case 0xcb: printf("JMP $%02x%02x",code[2],code[1]); opbytes = 3; break;
case 0xcc: printf("CZ $%02x%02x",code[2],code[1]); opbytes = 3; break;
case 0xcd: printf("CALL $%02x%02x",code[2],code[1]); opbytes = 3; break;
case 0xce: printf("ACI #$%02x",code[1]); opbytes = 2; break;
case 0xcf: printf("RST 1"); break;
case 0xd0: printf("RNC"); break;
case 0xd1: printf("POP D"); break;
case 0xd2: printf("JNC $%02x%02x",code[2],code[1]); opbytes = 3; break;
case 0xd3: printf("OUT #$%02x",code[1]); opbytes = 2; break;
case 0xd4: printf("CNC $%02x%02x",code[2],code[1]); opbytes = 3; break;
case 0xd5: printf("PUSH D"); break;
case 0xd6: printf("SUI #$%02x",code[1]); opbytes = 2; break;
case 0xd7: printf("RST 2"); break;
case 0xd8: printf("RC"); break;
case 0xd9: printf("RET"); break;
case 0xda: printf("JC $%02x%02x",code[2],code[1]); opbytes = 3; break;
case 0xdb: printf("IN #$%02x",code[1]); opbytes = 2; break;
case 0xdc: printf("CC $%02x%02x",code[2],code[1]); opbytes = 3; break;
case 0xdd: printf("CALL $%02x%02x",code[2],code[1]); opbytes = 3; break;
case 0xde: printf("SBI #$%02x",code[1]); opbytes = 2; break;
case 0xdf: printf("RST 3"); break;
case 0xe0: printf("RPO"); break;
case 0xe1: printf("POP H"); break;
case 0xe2: printf("JPO $%02x%02x",code[2],code[1]); opbytes = 3; break;
case 0xe3: printf("XTHL");break;
case 0xe4: printf("CPO $%02x%02x",code[2],code[1]); opbytes = 3; break;
case 0xe5: printf("PUSH H"); break;
case 0xe6: printf("ANI #$%02x",code[1]); opbytes = 2; break;
case 0xe7: printf("RST 4"); break;
case 0xe8: printf("RPE"); break;
case 0xe9: printf("PCHL");break;
case 0xea: printf("JPE $%02x%02x",code[2],code[1]); opbytes = 3; break;
case 0xeb: printf("XCHG"); break;
case 0xec: printf("CPE $%02x%02x",code[2],code[1]); opbytes = 3; break;
case 0xed: printf("CALL $%02x%02x",code[2],code[1]); opbytes = 3; break;
case 0xee: printf("XRI #$%02x",code[1]); opbytes = 2; break;
case 0xef: printf("RST 5"); break;
case 0xf0: printf("RP"); break;
case 0xf1: printf("POP PSW"); break;
case 0xf2: printf("JP $%02x%02x",code[2],code[1]); opbytes = 3; break;
case 0xf3: printf("DI"); break;
case 0xf4: printf("CP $%02x%02x",code[2],code[1]); opbytes = 3; break;
case 0xf5: printf("PUSH PSW"); break;
case 0xf6: printf("ORI #$%02x",code[1]); opbytes = 2; break;
case 0xf7: printf("RST 6"); break;
case 0xf8: printf("RM"); break;
case 0xf9: printf("SPHL");break;
case 0xfa: printf("JM $%02x%02x",code[2],code[1]); opbytes = 3; break;
case 0xfb: printf("EI"); break;
case 0xfc: printf("CM $%02x%02x",code[2],code[1]); opbytes = 3; break;
case 0xfd: printf("CALL $%02x%02x",code[2],code[1]); opbytes = 3; break;
case 0xfe: printf("CPI #$%02x",code[1]); opbytes = 2; break;
case 0xff: printf("RST 7"); break;
}
printf("\n");
return opbytes;
}
static void unimplementedInstruction(State8080* state) {
// pc will have advanced one, so undo that
printf ("Error: Unimplemented instruction\n");
exit(1);
}
static int parity(int x, int size) {
int i;
int p = 0;
x = (x & ((1<<size)-1));
for (i=0; i<size; i++)
{
if (x & 0x1) p++;
x = x >> 1;
}
return (0 == (p & 0x1));
}
static uint8_t machineIN(State8080* state, uint8_t port) {
uint8_t a;
switch(port)
{
case 1:
a = state->port.read1;
break;
case 2:
a = state->port.read2;
break;
case 3:
{
uint16_t v = (state->port.shift1<<8) | state->port.shift0;
a = ((v >> (8 - state->port.write2)) & 0xff);
break;
}
default:
unimplementedInstruction(state);
break;
}
return a;
}
static void machineOUT(State8080* state, uint8_t port) {
switch(port)
{
case 2:
state->port.write2 = state->a & 0x7;
break;
case 4:
state->port.shift0 = state->port.shift1;
state->port.shift1 = state->a;
break;
}
}
int emulate8080(State8080* state) {
unsigned char *opcode = &state->memory[state->pc];
// disassemble8080Op(opcode, state->pc);
state->pc += 1;
switch(*opcode) {
case 0x00: // NOP
break;
case 0x01: // LXI B, word
state->c = opcode[1];
state->b = opcode[2];
state->pc += 2; // Advance 2 more bytes
break;
case 0x02: // STAX B
{
uint16_t pair = (state->b << 8) | (state->c);
state->memory[pair] = state->a;
break;
}
case 0x03: // INX B
{
uint16_t pair = (state->b << 8) | (state->c);
pair = pair + 1;
state->b = (pair & 0xff00) >> 8;
state->c = pair & 0xff;
break;
}
case 0x04: // INR B
state->b = state->b + 1;
state->cc.z = ((state->b) == 0);
state->cc.s = ((state->b & 0x80) == 0x80);
state->cc.p = parity(state->b, 8);
state->cc.ac = ((state->b & 0xf) == 0xf);
break;
case 0x05: // DCR B
state->b = state->b - 1;
state->cc.z = ((state->b) == 0);
state->cc.s = ((state->b & 0x80) == 0x80);
state->cc.p = parity(state->b, 8);
state->cc.ac = ((state->b & 0xf) == 0x0);
break;
case 0x06: // MVI B, byte
state->b = opcode[1];
state->pc++; // for the data byte
break;
case 0x07: // RLC
{
uint8_t x = state->a;
state-> a = ((x << 1) | (x & 0x80) >> 7);
state->cc.cy = ((x & 0x80) == 0x80);
break;
}
case 0x09: // DAD B
{
uint32_t pairHL = (state->h << 8) | (state->l);
uint32_t pairBC = (state->b << 8) | (state->c);
pairHL = pairHL + pairBC;
state->cc.cy = (pairHL > 0xff);
state->h = (pairHL & 0xff00) >> 8;
state->l = pairHL & 0xff;
break;
}
case 0x0A: // LDAX B
{
uint16_t pair = (state->b << 8) | (state->c);
state->a = state->memory[pair];
break;
}
case 0x0B: // DCX B
{
uint16_t pair = (state->b << 8) | (state->c);
pair = pair - 1;
state->b = (pair & 0xff00) >> 8;
state->c = pair & 0xff;
break;
}
case 0x0C: // INR C
state->c = state->c + 1;
state->cc.z = ((state->c) == 0);
state->cc.s = ((state->c & 0x80) == 0x80);
state->cc.p = parity(state->c, 8);
state->cc.ac = ((state->c & 0xf) == 0xf);
break;
case 0x0D: // DCR C
state->c = state->c - 1;
state->cc.z = ((state->c) == 0);
state->cc.s = ((state->c & 0x80) == 0x80);
state->cc.p = parity(state->c, 8);
state->cc.ac = ((state->c & 0xf) == 0x0);
break;
case 0x0E: // MVI C, byte
state->c = opcode[1];
state->pc++; // for the data byte
break;
case 0x0F: // RRC
{
uint8_t x = state->a;
state-> a = ((x & 1) << 7 | (x >> 1));
state->cc.cy = ((x & 1) == 1);
break;
}
case 0x11: // LXI D, word
state->e = opcode[1];
state->d = opcode[2];
state->pc += 2; // Advance 2 more bytes
break;
case 0x12: // STAX D
{
uint16_t pair = (state->d << 8) | (state->e);
state->memory[pair] = state->a;
break;
}
case 0x13: // INX D
{
uint16_t pair = (state->d << 8) | (state->e);
pair = pair + 1;
state->d = (pair & 0xff00) >> 8;
state->e = pair & 0xff;
break;
}
case 0x14: // INR D
state->d = state->d + 1;
state->cc.z = ((state->d) == 0);
state->cc.s = ((state->d & 0x80) == 0x80);
state->cc.p = parity(state->d, 8);
state->cc.ac = ((state->d & 0xf) == 0xf);
break;
case 0x15: // DCR D
state->d = state->d - 1;
state->cc.z = ((state->d) == 0);
state->cc.s = ((state->d & 0x80) == 0x80);
state->cc.p = parity(state->d, 8);
state->cc.ac = ((state->d & 0xf) == 0x0);
break;
case 0x16: // MVI D, byte
state->d = opcode[1];
state->pc++; // for the data byte
break;
case 0x17: // RAL
{
uint8_t x = state->a;
state-> a = ((x << 1) | state->cc.cy);
state->cc.cy = ((x & 0x80) == 0x80);
break;
}
case 0x19: // DAD D
{
uint32_t pairHL = (state->h << 8) | (state->l);
uint32_t pairDE = (state->d << 8) | (state->e);
pairHL = pairHL + pairDE;
state->cc.cy = (pairHL > 0xff);
state->h = (pairHL & 0xff00) >> 8;
state->l = pairHL & 0xff;
break;
}
case 0x1A: // LDAX D
{
uint16_t pair = (state->d << 8) | (state->e);
state->a = state->memory[pair];
break;
}
case 0x1B: // DCX D
{
uint16_t pair = (state->d << 8) | (state->e);
pair = pair - 1;
state->b = (pair & 0xff00) >> 8;
state->e = pair & 0xff;
break;
}
case 0x1C: // INR E
state->e = state->e + 1;
state->cc.z = ((state->e) == 0);
state->cc.s = ((state->e & 0x80) == 0x80);
state->cc.p = parity(state->e, 8);
state->cc.ac = ((state->e & 0xf) == 0xf);
break;
case 0x1D: // DCR E
state->e = state->e - 1;
state->cc.z = ((state->e) == 0);
state->cc.s = ((state->e & 0x80) == 0x80);
state->cc.p = parity(state->e, 8);
state->cc.ac = ((state->e & 0xf) == 0x0);
break;
case 0x1E: // MVI E, byte
state->e = opcode[1];
state->pc++; // for the data byte
break;
case 0x1F: // RAR
{
uint8_t x = state->a;
state-> a = ((state->cc.cy << 7) | (x >> 1));
state->cc.cy = ((x & 1) == 1);
break;
}
case 0x20:
{
break;
}
case 0x21: // LXI H, word
state->l = opcode[1];
state->h = opcode[2];
state->pc += 2; // Advance 2 more bytes
break;
case 0x22: // SHLD adr
{
uint16_t adr = (opcode[2] << 8) | (opcode[1]);
state->memory[adr] = state->l;
state->memory[adr+1] = state->h;
state->pc += 2;
break;
}
case 0x23: // INX H
{
uint16_t pair = (state->h << 8) | (state->l);
pair = pair + 1;
state->h = (pair & 0xff00) >> 8;
state->l = pair & 0xff;
break;
}
case 0x24: // INR H
state->h = state->h + 1;
state->cc.z = ((state->h) == 0);
state->cc.s = ((state->h & 0x80) == 0x80);
state->cc.p = parity(state->h, 8);
state->cc.ac = ((state->h & 0xf) == 0xf);
break;
case 0x25: // DCR H
state->h = state->h - 1;
state->cc.z = ((state->h) == 0);
state->cc.s = ((state->h & 0x80) == 0x80);
state->cc.p = parity(state->h, 8);
state->cc.ac = ((state->h & 0xf) == 0x0);
break;
case 0x26: // MVI H, byte
state->h = opcode[1];
state->pc++; // for the data byte
break;
case 0x29: // DAD H
{
uint32_t pairHL = (state->h << 8) | (state->l);
pairHL = pairHL + pairHL;
state->cc.cy = (pairHL > 0xff);
state->h = (pairHL & 0xff00) >> 8;
state->l = pairHL & 0xff;
break;
}
case 0x2A: //LHLD addr
{
uint16_t adr = (opcode[2] << 8) | (opcode[1]);
state->l = state->memory[adr];
state->h = state->memory[adr+1];
state->pc += 2;
break;
}
case 0x2B: // DCX H
{
uint16_t pair = (state->h << 8) | (state->l);
pair = pair - 1;
state->b = (pair & 0xff00) >> 8;
state->l = pair & 0xff;
break;
}
case 0x2C: // INR L
state->l = state->l + 1;
state->cc.z = ((state->l) == 0);
state->cc.s = ((state->l & 0x80) == 0x80);
state->cc.p = parity(state->l, 8);
state->cc.ac = ((state->l & 0xf) == 0xf);
break;
case 0x2D: // DCR L
state->l = state->l - 1;
state->cc.z = ((state->l) == 0);
state->cc.s = ((state->l & 0x80) == 0x80);
state->cc.p = parity(state->l, 8);
state->cc.ac = ((state->l & 0xf) == 0x0);
break;
case 0x2E: // MVI l, byte
state->l = opcode[1];
state->pc++; // for the data byte
break;
case 0x2F: // CMA (not)
state->a = ~state->a;
break;
case 0x31: // LXI SP, word
state->sp = (opcode[2] << 8) | (opcode[1]);
state->pc += 2; // Advance 2 more bytes
break;
case 0x32: // STA adr
{
uint16_t adr = (opcode[2] << 8) | (opcode[1]);
state->memory[adr] = state->a;
state->pc += 2;
break;
}
case 0x33: // INX M
{
uint16_t pair = (state->h << 8) | (state->l);
pair = pair + 1;
state->h = (pair & 0xff00) >> 8;
state->l = pair & 0xff;
break;
}
case 0x34: // INR M
{
uint16_t offset = (state->h << 8) | (state->l);
state->memory[offset] = state->memory[offset] + 1;
state->cc.z = ((state->memory[offset]) == 0);
state->cc.s = ((state->memory[offset] & 0x80) == 0x80);
state->cc.p = parity(state->memory[offset], 8);
state->cc.ac = ((state->memory[offset] & 0xf) == 0xf);
break;
}
case 0x35: // DCR M
{
uint16_t offset = (state->h << 8) | (state->l);
state->memory[offset] = state->memory[offset] - 1;
state->cc.z = ((state->memory[offset]) == 0);
state->cc.s = ((state->memory[offset] & 0x80) == 0x80);
state->cc.p = parity(state->memory[offset], 8);
state->cc.ac = ((state->memory[offset] & 0xf) == 0x0);
break;
}
case 0x36: // MVI M, byte
{
uint16_t offset = (state->h << 8) | (state->l);
state->memory[offset] = opcode[1];
state->pc++; // for the data byte
break;
}
case 0x37: // STC
state->cc.cy = 1;
break;
case 0x38:
break;
case 0x39: // DAD SP
{
uint32_t pairHL = (state->h << 8) | (state->l);
pairHL = pairHL + (uint32_t) state->sp;
state->cc.cy = (pairHL > 0xff);
state->h = (pairHL & 0xff00) >> 8;
state->l = pairHL & 0xff;
break;
}
case 0x3A: // LDA adr
{
uint16_t adr = (opcode[2] << 8) | (opcode[1]);
state->a = state->memory[adr];
state->pc += 2;
break;
}
case 0x3B: // DCX SP
state->sp = state->sp - 1;
state->b = (state->sp & 0xff00) >> 8;
state->l = state->sp & 0xff;
break;
case 0x3C: // INR A
state->a = state->a + 1;
state->cc.z = ((state->a) == 0);
state->cc.s = ((state->a & 0x80) == 0x80);
state->cc.p = parity(state->a, 8);
state->cc.ac = ((state->a & 0xf) == 0xf);
break;
case 0x3D: // DCR A
state->a = state->a - 1;
state->cc.z = ((state->a) == 0);
state->cc.s = ((state->a & 0x80) == 0x80);
state->cc.p = parity(state->a, 8);
state->cc.ac = ((state->a & 0xf) == 0x0);
break;
case 0x3E: // MVI A, byte
state->a = opcode[1];
state->pc++; // for the data byte
break;
case 0x3F: // CMC
state->cc.cy = !state->cc.cy;
break;
case 0x40: // MOV B, B
state->b = state->b;
break;
case 0x41: // MOV B, C
state->b = state->c;
break;
case 0x42: // MOV B, D
state->b = state->d;
break;
case 0x43: // MOV B, E
state->b = state->e;
break;
case 0x44: // MOV B, H
state->b = state->h;
break;
case 0x45: // MOV B, L
state->b = state->l;
break;
case 0x46: // MOV B, M
{
uint16_t offset = (state->h << 8) | (state->l);
state->b = state->memory[offset];
break;
}
case 0x47: // MOV B, A
state->b = state->a;
break;
case 0x48: // MOV C, B
state->c = state->b;
break;
case 0x49: // MOV C, C
state->c = state->c;
break;
case 0x4A: // MOV C, D
state->c = state->d;
break;
case 0x4B: // MOV C, E
state->c = state->e;
break;
case 0x4C: // MOV C, H
state->c = state->h;
break;
case 0x4D: // MOV C, L
state->c = state->l;
break;
case 0x4E: // MOV C, M
{
uint16_t offset = (state->h << 8) | (state->l);
state->c = state->memory[offset];
break;
}
case 0x4F: // MOV C, A
state->c = state->a;
break;
case 0x50: // MOV D, B
state->d = state->b;
break;
case 0x51: // MOV D, C
state->d = state->c;
break;
case 0x52: // MOV D, D
state->d = state->d;
break;
case 0x53: // MOV D, E
state->d = state->e;
break;
case 0x54: // MOV D, H
state->d = state->h;
break;
case 0x55: // MOV D, L
state->d = state->l;
break;
case 0x56: // MOV D, M
{
uint16_t offset = (state->h << 8) | (state->l);
state->d = state->memory[offset];
break;
}
case 0x57: // MOV D, A
state->d = state->a;
break;
case 0x58: // MOV E, B
state->e = state->b;
break;
case 0x59: // MOV E, C
state->e = state->c;
break;
case 0x5A: // MOV E, D
state->e = state->d;
break;
case 0x5B: // MOV E, E
state->e = state->e;
break;
case 0x5C: // MOV E, H
state->e = state->h;
break;
case 0x5D: // MOV E, L
state->e = state->l;
break;
case 0x5E: // MOV E, M
{
uint16_t offset = (state->h << 8) | (state->l);
state->e = state->memory[offset];
break;
}
case 0x5F: // MOV E, A
state->e = state->a;
break;
case 0x60: // MOV H, B
state->h = state->b;
break;
case 0x61: // MOV H, C
state->h = state->c;
break;
case 0x62: // MOV H, D
state->h = state->d;
break;
case 0x63: // MOV H, E
state->h = state->e;
break;
case 0x64: // MOV H, H
state->h = state->h;
break;
case 0x65: // MOV H, L
state->h = state->l;
break;
case 0x66: // MOV H, M
{
uint16_t offset = (state->h << 8) | (state->l);
state->h = state->memory[offset];
break;
}
case 0x67: // MOV H, A
state->h = state->a;
break;
case 0x68: // MOV L, B
state->l = state->b;
break;
case 0x69: // MOV L, C
state->l = state->c;
break;
case 0x6A: // MOV L, D
state->l = state->d;
break;
case 0x6B: // MOV L, E
state->l = state->e;
break;
case 0x6C: // MOV L, H
state->l = state->h;
break;
case 0x6D: // MOV L, L
state->l = state->l;
break;
case 0x6E: // MOV L, M
{
uint16_t offset = (state->h << 8) | (state->l);
state->l = state->memory[offset];
break;
}
case 0x6F: // MOV L, A
state->l = state->a;
break;
case 0x70: // MOV M, B
{
uint16_t offset = (state->h << 8) | (state->l);
state->memory[offset] = state->b;
break;
}
case 0x71: // MOV M, C
{
uint16_t offset = (state->h << 8) | (state->l);
state->memory[offset] = state->c;
break;
}
case 0x72: // MOV M, D
{
uint16_t offset = (state->h << 8) | (state->l);
state->memory[offset] = state->d;
break;
}
case 0x73: // MOV M, E
{
uint16_t offset = (state->h << 8) | (state->l);
state->memory[offset] = state->e;
break;
}
case 0x74: // MOV M, H
{
uint16_t offset = (state->h << 8) | (state->l);
state->memory[offset] = state->h;
break;
}
case 0x75: // MOV M, L
{
uint16_t offset = (state->h << 8) | (state->l);
state->memory[offset] = state->l;
break;
}
case 0x76: // HLT
exit(0);
case 0x77: // MOV B, A
{
uint16_t offset = (state->h << 8) | (state->l);
state->memory[offset] = state->a;
break;
}
case 0x78: // MOV A, B
state->a = state->b;
break;
case 0x79: // MOV A, C
state->a = state->c;
break;
case 0x7A: // MOV A, D
state->a = state->d;
break;
case 0x7B: // MOV A, E
state->a = state->e;
break;
case 0x7C: // MOV A, H
state->a = state->h;
break;
case 0x7D: // MOV A, L
state->a = state->l;
break;
case 0x7E: // MOV A, M
{
uint16_t offset = (state->h << 8) | (state->l);
state->a = state->memory[offset];
break;
}
case 0x7F: // MOV A, A
state->a = state->a;
break;
case 0x80: // ADD B
{
// do math with higher precision so we can capture the
// carry out
uint16_t answer = (uint16_t) state->a + (uint16_t) state ->b;
// Zero flag: if the result is zero,
// set the flag to zero
// else clear the flag
if ((answer & 0xff) == 0)
state->cc.z = 1;
else
state->cc.z = 0;
// Sign flag: if bit 7 is set,
// set the sign flag
// else clear the sign flag
if (answer & 0x80)
state->cc.s = 1;
else
state->cc.s = 0;
// Carry flag
if (answer > 0xff)
state->cc.cy = 1;
else
state->cc.cy = 0;
// Parity is handled by a subroutine
state->cc.p = parity(answer & 0xff, 8);
// Auxiliary Carry
if ((state->a & 0xf) + (state->b & 0xf) > 0xf)
state->cc.ac = 1;
else
state->cc.ac = 0;
state->a = answer & 0xff;
break;
}
// The code for ADD can be condensed like this