void disassembler::decode_modrm(x86_insn *insn)
{
insn->modrm = fetch_byte();
BX_DECODE_MODRM(insn->modrm, insn->mod, insn->nnn, insn->rm);
// MOVs with CRx and DRx always use register ops and ignore the mod field.
if ((insn->b1 & ~3) == 0x120) insn->mod = 3;
if (insn->mod == 3) {
/* mod, reg, reg */
return;
}
/* 16 bit addressing modes. */
switch (insn->mod) {
case 0:
resolve_modrm = &disassembler::resolve16_mod0;
if(insn->rm == 6)
insn->displacement.displ16 = fetch_word();
break;
case 1:
/* reg, 8-bit displacement, sign extend */
resolve_modrm = &disassembler::resolve16_mod1or2;
insn->displacement.displ16 = (int8) fetch_byte();
break;
case 2:
resolve_modrm = &disassembler::resolve16_mod1or2;
insn->displacement.displ16 = fetch_word();
break;
} /* switch (mod) ... */
}
static uint16_t ea_extended(struct MC6809 *cpu) {
unsigned ea = fetch_byte(cpu, REG_PC) << 8;
ea |= fetch_byte(cpu, REG_PC+1);
REG_PC += 2;
NVMA_CYCLE;
return ea;
}
static void take_interrupt(struct MC6809 *cpu, uint8_t mask, uint16_t vec) {
REG_CC |= mask;
NVMA_CYCLE;
DELEGATE_SAFE_CALL1(cpu->interrupt_hook, vec);
unsigned new_pc = fetch_byte(cpu, vec) << 8;
new_pc |= fetch_byte(cpu, vec+1);
REG_PC = new_pc;
NVMA_CYCLE;
}
void _ldyZp(void)
{
byte zaddr;
word res;
zaddr = fetch_byte((word)(cpu.pc + 1));
res = cpu.y = fetch_byte(zaddr);
set_nz(res);
cpu.pc += 2;
}
/*
* add with carry zero page mode
*/
void _adcZp(void)
{
byte zaddr, value;
zaddr = fetch_byte((word)(cpu.pc + 1));
value = fetch_byte(zaddr);
ADC(value);
cpu.pc += 2;
}
void _oraZpx(void)
{
byte zaddr;
word res;
zaddr = fetch_byte((word)(cpu.pc + 1));
zaddr += cpu.x;
res = cpu.a |= fetch_byte(zaddr);
set_nz(res);
cpu.pc += 2;
}
void _ldxZpy(void)
{
byte zaddr;
word res;
zaddr = fetch_byte((word)(cpu.pc + 1));
zaddr += cpu.y;
res = cpu.x = fetch_byte(zaddr);
set_nz(res);
cpu.pc += 2;
}
void _ldaIdy(void)
{
byte zaddr;
word addr;
word res;
zaddr = fetch_byte((word)(cpu.pc + 1));
addr = fetch_word(zaddr) + cpu.y;
res = cpu.a = fetch_byte(addr);
set_nz(res);
cpu.pc += 2;
}
void _eorZp(void)
{
byte addr;
word res;
addr = fetch_byte((word)(cpu.pc + 1));
res = cpu.a ^= fetch_byte(addr);
set_nz(res);
cpu.pc += 2;
}
void _sbcZpx(void)
{
byte zaddr, value;
zaddr = fetch_byte((word)(cpu.pc + 1));
zaddr += cpu.x;
value = fetch_byte(zaddr);
SBC(value);
cpu.pc += 2;
}
void disassembler::IbIb(const x86_insn *insn)
{
Bit8u ib1 = fetch_byte();
Bit8u ib2 = fetch_byte();
if (intel_mode) {
dis_sprintf("0x%02x, 0x%02x", ib1, ib2);
}
else {
dis_sprintf("$0x%02x, $0x%02x", ib2, ib1);
}
}
/*
* add with carry indirect, y mode
*/
void _adcIdy(void)
{
byte zaddr, value;
word addr;
zaddr = fetch_byte((word)(cpu.pc + 1));
addr = fetch_word(zaddr) + cpu.y;
value = fetch_byte(addr);
ADC(value);
cpu.pc += 2;
}
void _sbcIdx(void)
{
byte zaddr, value;
word addr;
zaddr = fetch_byte((word)(cpu.pc + 1));
zaddr += cpu.x;
addr = fetch_word(zaddr);
value = fetch_byte(addr);
SBC(value);
cpu.pc += 2;
}
void _cpyZp(void)
{
byte zaddr;
word res;
zaddr = fetch_byte((word)(cpu.pc + 1));
res = cpu.y - fetch_byte(zaddr);
set_carry(res < 0x100);
set_nz(res);
cpu.pc += 2;
}
void _cmpZpx(void)
{
byte zaddr;
word res;
zaddr = fetch_byte((word)(cpu.pc + 1));
zaddr += cpu.x;
res = cpu.a - fetch_byte(zaddr);
set_carry(res < 0x100);
set_nz(res);
cpu.pc += 2;
}
/*
* run the cpu
*/
void cpu_run(void)
{
byte i;
const Instr *pi;
cpu_reset();
do {
/* check for pending interrupts */
if (!get_int_disable_flag() && (pending_interrupt & HANDLE_IRQ))
DO_INTERRUPT();
if (pending_interrupt & HANDLE_NMI) {
pending_interrupt &= ~HANDLE_NMI;
DO_NMI();
}
/* fetch the next instruction */
i = fetch_byte(cpu.pc);
pi = instructions[i];
if (NULL == pi) {
warning("unrecognized instruction \"$%.2x\" at $%.4hx.\n",
i, cpu.pc);
break;
}
/* execute the instruction */
(*pi->fnc)();
} while (!err);
}
void _decZp(void)
{
byte addr;
word res;
addr = fetch_byte((word)(cpu.pc + 1));
res = fetch_byte(addr);
res = (res - 1) & 0xFF;
store_byte(addr, (byte)res);
set_nz(res);
cpu.pc += 2;
}
void _andIdx(void)
{
byte zaddr;
word addr;
word res;
zaddr = fetch_byte((word)(cpu.pc + 1));
zaddr += cpu.x;
addr = fetch_word(zaddr);
res = cpu.a &= fetch_byte(addr);
set_nz(res);
cpu.pc += 2;
}
void _incZpx(void)
{
byte addr;
word res;
addr = fetch_byte((word)(cpu.pc + 1));
addr += cpu.x;
res = fetch_byte(addr);
res = (res + 1) & 0xFF;
store_byte(addr, (byte)res);
set_nz(res);
cpu.pc += 2;
}
void _bcs(void)
{
byte b;
b = fetch_byte((word)(cpu.pc + 1));
cpu.pc += 2;
if (get_carry_flag())
branch(b);
}
void _cmpIdy(void)
{
byte zaddr;
word addr;
word res;
zaddr = fetch_byte((word)(cpu.pc + 1));
addr = fetch_word(zaddr) + cpu.y;
res = cpu.a - fetch_byte(addr);
set_carry(res < 0x100);
set_nz(res);
cpu.pc += 2;
}
void _bvs(void)
{
byte b;
b = fetch_byte((word)(cpu.pc + 1));
cpu.pc += 2;
if (get_overflow_flag())
branch(b);
}
void _bpl(void)
{
byte b;
b = fetch_byte((word)(cpu.pc + 1));
cpu.pc += 2;
if (!get_neg_flag())
branch(b);
}
void _bne(void)
{
byte b;
b = fetch_byte((word)(cpu.pc + 1));
cpu.pc += 2;
if (!get_zero_flag())
branch(b);
}
/*
* pop a value from the stack
*/
byte pop(void)
{
if (cpu.sp == STACKBEGIN) {
warning("stack underflow error.\n");
err = 1;
return 0;
}
return fetch_byte((word)(PAGEONE + ++cpu.sp));
}
void _aslZpx(void)
{
byte zaddr;
zaddr = fetch_byte((word)(cpu.pc + 1));
ASL((word)(zaddr + cpu.x));
cpu.pc += 2;
}
void _bitZp(void)
{
byte zaddr;
zaddr = fetch_byte((word)(cpu.pc + 1));
BIT(zaddr);
cpu.pc += 2;
}
void _aslZp(void)
{
byte zaddr;
zaddr = fetch_byte((word)(cpu.pc + 1));
ASL(zaddr);
cpu.pc += 2;
}
/*
* add with carry immediate mode
*/
void _adcImm(void)
{
byte value;
value = fetch_byte((word)(cpu.pc + 1));
ADC(value);
cpu.pc += 2;
}
void _styZpx(void)
{
byte zaddr;
zaddr = fetch_byte((word)(cpu.pc + 1));
zaddr += cpu.x;
store_byte(zaddr, cpu.y);
cpu.pc += 2;
}