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Add function to write data onto bus according to choosen addressing mode.

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This commit is contained in:
Radosław Kujawa 2017-01-21 21:43:31 +01:00
parent 8abbb88d0d
commit 86c9c6414c
2 changed files with 39 additions and 0 deletions
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38
src/instruction.c
View File

@ -162,6 +162,44 @@ instruction_status_adjust_negative(rk65c02emu_t *e, uint8_t regval)
e->regs.P &= ~P_NEGATIVE;
}
void
instruction_data_write_1(rk65c02emu_t *e, instrdef_t *id, instruction_t *i, uint8_t val)
{
uint16_t iaddr;
switch (id->mode) {
case ZP:
bus_write_1(e->bus, i->op1, val);
break;
case ZPX:
/* XXX: wraps around zero page? */
bus_write_1(e->bus, i->op1 + e->regs.X, val);
break;
case ZPY:
bus_write_1(e->bus, i->op1 + e->regs.Y, val);
break;
case IZP:
iaddr = bus_read_1(e->bus, i->op1);
iaddr |= (bus_read_1(e->bus, i->op1 + 1) << 8);
bus_write_1(e->bus, iaddr, val);
break;
case ACCUMULATOR:
case IMMEDIATE:
case IZPX:
case IZPY:
case RELATIVE:
case ABSOLUTE:
case ABSOLUTEX:
case ABSOLUTEY:
case IABSOLUTE:
case IABSOLUTEX:
default:
printf("unhandled addressing mode for opcode %x\n",
i->opcode);
break;
}
}
uint8_t
instruction_data_read_1(rk65c02emu_t *e, instrdef_t *id, instruction_t *i)
{

1
src/instruction.h
View File

@ -44,6 +44,7 @@ instrdef_t instruction_decode(uint8_t);
void instruction_print(instruction_t *);
void disassemble(bus_t *, uint16_t);
uint8_t instruction_data_read_1(rk65c02emu_t *, instrdef_t *, instruction_t *);
void instruction_data_write_1(rk65c02emu_t *, instrdef_t *, instruction_t *, uint8_t);
void instruction_status_adjust_zero(rk65c02emu_t *, uint8_t);
void instruction_status_adjust_negative(rk65c02emu_t *, uint8_t);
void stack_push(rk65c02emu_t *, uint8_t);