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Split address calculation into separate function.

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This removes some code duplication for instruction_data_read/write
functions. Also this way implementing watchpoints will be far easier.
This commit is contained in:
Radosław Kujawa 2018-04-27 10:34:48 +02:00
parent 216450da52
commit b7986df553
2 changed files with 39 additions and 77 deletions
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115
src/instruction.c
View File

@ -275,110 +275,71 @@ instruction_status_adjust_negative(rk65c02emu_t *e, uint8_t regval)
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:
case ZPR:
bus_write_1(e->bus, i->op1, val);
break;
case ZPX:
bus_write_1(e->bus, (uint8_t) (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 ABSOLUTE:
bus_write_1(e->bus, i->op1 + (i->op2 << 8), val);
break;
case IZPX: /* Zero Page Indexed Indirect with X */
iaddr = bus_read_1(e->bus,(uint8_t) (i->op1 + e->regs.X));
iaddr |= (bus_read_1(e->bus, (uint8_t) (i->op1 + e->regs.X + 1)) << 8);
bus_write_1(e->bus, iaddr, val);
break;
case IZPY: /* Zero Page Indirect Indexed with Y */
iaddr = bus_read_1(e->bus, i->op1);
iaddr |= (bus_read_1(e->bus, i->op1 + 1) << 8);
bus_write_1(e->bus, iaddr + e->regs.Y, val);
break;
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 ACCUMULATOR:
if (id->mode == ACCUMULATOR) {
e->regs.A = val;
break;
case IMMEDIATE:
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:
rk65c02_panic(e, "unhandled addressing mode for opcode %x\n",
i->opcode);
break;
return;
}
if (id->mode == IMMEDIATE) {
rk65c02_panic(e,
"invalid IMMEDIATE addressing mode for opcode %x\n",
i->opcode);
return;
}
bus_write_1(e->bus, instruction_data_address(e, id, i), val);
}
uint8_t
instruction_data_read_1(rk65c02emu_t *e, instrdef_t *id, instruction_t *i)
{
uint8_t rv; /* data read from the bus */
uint16_t iaddr; /* indirect address */
if (id->mode == ACCUMULATOR)
return e->regs.A;
else if (id->mode == IMMEDIATE)
return i->op1;
rv = 0;
return bus_read_1(e->bus, instruction_data_address(e, id, i));
}
uint16_t
instruction_data_address(rk65c02emu_t *e, instrdef_t *id, instruction_t *i)
{
uint16_t addr;
addr = 0;
switch (id->mode) {
case ACCUMULATOR:
rv = e->regs.A;
break;
case IMMEDIATE:
rv = i->op1;
break;
case ZP:
case ZPR:
rv = bus_read_1(e->bus, i->op1);
addr = i->op1;
break;
case ZPX:
rv = bus_read_1(e->bus, (uint8_t) (i->op1 + e->regs.X));
addr = ((uint8_t) (i->op1 + e->regs.X));
break;
case ZPY:
rv = bus_read_1(e->bus, i->op1 + e->regs.Y);
addr = i->op1 + e->regs.Y;
break;
case IZP:
iaddr = bus_read_1(e->bus, i->op1);
iaddr |= (bus_read_1(e->bus, i->op1 + 1) << 8);
rv = bus_read_1(e->bus, iaddr);
addr = bus_read_1(e->bus, i->op1);
addr |= (bus_read_1(e->bus, i->op1 + 1) << 8);
break;
case IZPX: /* Zero Page Indexed Indirect with X */
iaddr = bus_read_1(e->bus, (uint8_t) (i->op1 + e->regs.X));
iaddr |= (bus_read_1(e->bus, (uint8_t) (i->op1 + e->regs.X + 1)) << 8);
rv = bus_read_1(e->bus, iaddr);
addr = bus_read_1(e->bus, (uint8_t) (i->op1 + e->regs.X));
addr |= (bus_read_1(e->bus, (uint8_t) (i->op1 + e->regs.X + 1)) << 8);
break;
case IZPY: /* Zero Page Indirect Indexed with Y */
iaddr = bus_read_1(e->bus, i->op1);
iaddr |= (bus_read_1(e->bus, i->op1 + 1) << 8);
rv = bus_read_1(e->bus, iaddr + e->regs.Y);
addr = bus_read_1(e->bus, i->op1);
addr |= (bus_read_1(e->bus, i->op1 + 1) << 8);
addr += e->regs.Y;
break;
case ABSOLUTE:
rv = bus_read_1(e->bus, i->op1 + (i->op2 << 8));
addr = i->op1 + (i->op2 << 8);
break;
case ABSOLUTEX:
rv = bus_read_1(e->bus, (i->op1 + (i->op2 << 8)) + e->regs.X);
addr = 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);
addr = i->op1 + (i->op2 << 8) + e->regs.Y;
break;
case IABSOLUTE:
case IABSOLUTEX:
@ -394,7 +355,7 @@ instruction_data_read_1(rk65c02emu_t *e, instrdef_t *id, instruction_t *i)
break;
}
return rv;
return addr;
}
/* put value onto the stack */

1
src/instruction.h
View File

@ -55,6 +55,7 @@ char * instruction_string_get(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);
uint16_t instruction_data_address(rk65c02emu_t *e, instrdef_t *id, instruction_t *i);
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);