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Implement absolute X, absolute Y addressing.

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This commit is contained in:
Radosław Kujawa 2017-01-23 10:48:37 +01:00
parent 452e4b3806
commit ee16c64310
1 changed files with 21 additions and 1 deletions
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22
src/instruction.c
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@ -189,18 +189,29 @@ instruction_data_write_1(rk65c02emu_t *e, instrdef_t *id, instruction_t *i, uint
case ACCUMULATOR:
case IMMEDIATE:
case IZPX:
/* XXX */
iaddr = bus_read_1(e->bus, i->op1 + e->regs.X);
iaddr |= (bus_read_1(e->bus, i->op1 + e->regs.X + 1) << 8);
bus_write_1(e->bus, iaddr, val);
case IZPY:
/* XXX */
iaddr = bus_read_1(e->bus, i->op1 + e->regs.Y);
iaddr |= (bus_read_1(e->bus, i->op1 + e->regs.Y + 1) << 8);
bus_write_1(e->bus, iaddr, val);
case RELATIVE:
case ABSOLUTEX:
bus_write_1(e->bus, (i->op1 + (i->op2 << 8)) + e->regs.X, val);
break;
case ABSOLUTEY:
bus_write_1(e->bus, (i->op1 + (i->op2 << 8)) + e->regs.Y, val);
break;
case RELATIVE:
case IABSOLUTE:
case IABSOLUTEX:
/*
* IABSOLUTE, IABSOLUTEX, RELATIVE are only for branches
* and jumps. They do not read or write anything, only modify
* PC which is handled within emulation of a given opcode.
*/
default:
printf("unhandled addressing mode for opcode %x\n",
i->opcode);
@ -255,10 +266,19 @@ instruction_data_read_1(rk65c02emu_t *e, instrdef_t *id, instruction_t *i)
rv = bus_read_1(e->bus, i->op1 + (i->op2 << 8));
break;
case ABSOLUTEX:
rv = bus_read_1(e->bus, (i->op1 + (i->op2 << 8)) + e->regs.X);
break;
case ABSOLUTEY:
rv = bus_read_1(e->bus, (i->op1 + (i->op2 << 8)) + e->regs.Y);
break;
case IABSOLUTE:
case IABSOLUTEX:
case RELATIVE:
/*
* IABSOLUTE, IABSOLUTEX, RELATIVE are only for branches
* and jumps. They do not read or write anything, only modify
* PC which is handled within emulation of a given opcode.
*/
default:
printf("unhandled addressing mode for opcode %x\n",
i->opcode);