ewm/mem.c
2016-11-18 16:50:31 -05:00

213 lines
6.9 KiB
C

// The MIT License (MIT)
//
// Copyright (c) 2015 Stefan Arentz - http://github.com/st3fan/ewm
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.
#include <assert.h>
#include <stdio.h>
#include <stdlib.h>
#include "cpu.h"
#include "mem.h"
// The following two are our memory primitives that properly set go
// through the handler functions for all registered memory. They will
// take more time but do the right thing.
uint8_t mem_get_byte(struct cpu_t *cpu, uint16_t addr) {
struct mem_t *mem = cpu->mem;
while (mem != NULL) {
if (addr >= mem->start && (addr <= (mem->start + mem->length))) {
if (mem->read_handler) {
return ((mem_read_handler_t) mem->read_handler)((struct cpu_t*) cpu, mem, addr);
} else {
if (cpu->strict) {
// TODO: Signal an error about reading to write-only region (does that even exist?)
}
return 0;
}
}
mem = mem->next;
}
if (cpu->strict) {
// TODO: Signal an error about reading non-existent memory
}
return 0; // TODO What should the default be if we read from non-existent memory?
}
void mem_set_byte(struct cpu_t *cpu, uint16_t addr, uint8_t v) {
struct mem_t *mem = cpu->mem;
while (mem != NULL) {
if (addr >= mem->start && (addr <= (mem->start + mem->length))) {
if (mem->write_handler) {
((mem_write_handler_t) mem->write_handler)((struct cpu_t*) cpu, mem, addr, v);
} else {
if (cpu->strict) {
// TODO: Signal an error about writing to read-only region
}
}
return;
}
mem = mem->next;
}
if (cpu->strict) {
// TODO: Signal an error about writing non-existent memory
}
}
// Getters
uint8_t mem_get_byte_abs(struct cpu_t *cpu, uint16_t addr) {
return mem_get_byte(cpu, addr);
}
uint8_t mem_get_byte_absx(struct cpu_t *cpu, uint16_t addr) {
return mem_get_byte(cpu, addr + cpu->state.x); /* TODO: Carry? */
}
uint8_t mem_get_byte_absy(struct cpu_t *cpu, uint16_t addr) {
return mem_get_byte(cpu, addr + cpu->state.y); /* TODO: Carry? */
}
uint8_t mem_get_byte_zpg(struct cpu_t *cpu, uint8_t addr) {
return mem_get_byte(cpu, addr);
}
uint8_t mem_get_byte_zpgx(struct cpu_t *cpu, uint8_t addr) {
return mem_get_byte(cpu, ((uint16_t) addr + cpu->state.x) & 0x00ff);
}
uint8_t mem_get_byte_zpgy(struct cpu_t *cpu, uint8_t addr) {
return mem_get_byte(cpu, ((uint16_t) addr + cpu->state.y) & 0x00ff);
}
uint8_t mem_get_byte_indx(struct cpu_t *cpu, uint8_t addr) {
return mem_get_byte(cpu, mem_get_word(cpu, addr + cpu->state.x)); // TODO: Does this wrap?
}
uint8_t mem_get_byte_indy(struct cpu_t *cpu, uint8_t addr) {
return mem_get_byte(cpu, mem_get_word(cpu, addr) + cpu->state.y);
}
uint16_t mem_get_word(struct cpu_t *cpu, uint16_t addr) {
// TODO Did I do this right?
return ((uint16_t) mem_get_byte(cpu, addr+1) << 8) | (uint16_t) mem_get_byte(cpu, addr);
}
// Setters
void mem_set_byte_zpg(struct cpu_t *cpu, uint8_t addr, uint8_t v) {
mem_set_byte(cpu, addr, v);
}
void mem_set_byte_zpgx(struct cpu_t *cpu, uint8_t addr, uint8_t v) {
mem_set_byte(cpu, ((uint16_t) addr + cpu->state.x) & 0x00ff, v);
}
void mem_set_byte_zpgy(struct cpu_t *cpu, uint8_t addr, uint8_t v) {
mem_set_byte(cpu, ((uint16_t) addr + cpu->state.y) & 0x00ff, v);
}
void mem_set_byte_abs(struct cpu_t *cpu, uint16_t addr, uint8_t v) {
mem_set_byte(cpu, addr, v);
}
void mem_set_byte_absx(struct cpu_t *cpu, uint16_t addr, uint8_t v) {
mem_set_byte(cpu, addr+cpu->state.x, v);
}
void mem_set_byte_absy(struct cpu_t *cpu, uint16_t addr, uint8_t v) {
mem_set_byte(cpu, addr+cpu->state.y, v);
}
void mem_set_byte_indx(struct cpu_t *cpu, uint8_t addr, uint8_t v) {
mem_set_byte(cpu, mem_get_word(cpu, addr+cpu->state.x), v); // TODO: Does this wrap?
}
void mem_set_byte_indy(struct cpu_t *cpu, uint8_t addr, uint8_t v) {
mem_set_byte(cpu, mem_get_word(cpu, addr)+cpu->state.y, v);
}
void mem_set_word(struct cpu_t *cpu, uint16_t addr, uint16_t v) {
mem_set_byte(cpu, addr+0, (uint8_t) v); // TODO Did I do this right?
mem_set_byte(cpu, addr+1, (uint8_t) (v >> 8));
}
/* MOD */
void mem_mod_byte_zpg(struct cpu_t *cpu, uint8_t addr, mem_mod_t op) {
mem_set_byte_zpg(cpu, addr, op(cpu, mem_get_byte_zpg(cpu, addr)));
}
void mem_mod_byte_zpgx(struct cpu_t *cpu, uint8_t addr, mem_mod_t op) {
mem_set_byte_zpgx(cpu, addr, op(cpu, mem_get_byte_zpgx(cpu, addr)));
}
void mem_mod_byte_zpgy(struct cpu_t *cpu, uint8_t addr, mem_mod_t op) {
mem_set_byte_zpgy(cpu, addr, op(cpu, mem_get_byte_zpgy(cpu, addr)));
}
void mem_mod_byte_abs(struct cpu_t *cpu, uint16_t addr, mem_mod_t op) {
mem_set_byte_abs(cpu, addr, op(cpu, mem_get_byte_abs(cpu, addr)));
}
void mem_mod_byte_absx(struct cpu_t *cpu, uint16_t addr, mem_mod_t op) {
mem_set_byte_absx(cpu, addr, op(cpu, mem_get_byte_absx(cpu, addr)));
}
void mem_mod_byte_absy(struct cpu_t *cpu, uint16_t addr, mem_mod_t op) {
mem_set_byte_absy(cpu, addr, op(cpu, mem_get_byte_absy(cpu, addr)));
}
void mem_mod_byte_indx(struct cpu_t *cpu, uint8_t addr, mem_mod_t op) {
mem_set_byte_indx(cpu, addr, op(cpu, mem_get_byte_indx(cpu, addr)));
}
void mem_mod_byte_indy(struct cpu_t *cpu, uint8_t addr, mem_mod_t op) {
mem_set_byte_indy(cpu, addr, op(cpu, mem_get_byte_indy(cpu, addr)));
}
// The following get and set memory directly. There are no checks, so
// make sure you are doing the right thing. Mainly used for managing
// the stack, reading instructions, reading vectors and tracing code.
uint8_t _mem_get_byte_direct(struct cpu_t *cpu, uint16_t addr) {
assert(addr <= 0x200);
return cpu->memory[addr];
}
uint16_t _mem_get_word_direct(struct cpu_t *cpu, uint16_t addr) {
assert(addr <= 0x200);
return *((uint16_t*) &cpu->memory[addr]);
}
void _mem_set_byte_direct(struct cpu_t *cpu, uint16_t addr, uint8_t v) {
assert(addr <= 0x200);
cpu->memory[addr] = v;
}
void _mem_set_word_direct(struct cpu_t *cpu, uint16_t addr, uint16_t v) {
assert(addr <= 0x200);
*((uint16_t*) &cpu->memory[addr]) = v;
}