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