mirror of https://git.sr.ht/~rabbits/uxn
147 lines
2.4 KiB
C
147 lines
2.4 KiB
C
#include <stdio.h>
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/*
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Copyright (c) 2021 Devine Lu Linvega
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Permission to use, copy, modify, and distribute this software for any
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purpose with or without fee is hereby granted, provided that the above
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copyright notice and this permission notice appear in all copies.
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THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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WITH REGARD TO THIS SOFTWARE.
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*/
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#define FLAG_HALT 0x01
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#define FLAG_ZERO 0x02
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#define FLAG_CARRY 0x04
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#define FLAG_TRAPS 0x08
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#define STACK_DEPTH 256
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typedef unsigned char Uint8;
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typedef struct {
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Uint8 literal;
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Uint8 status, counter;
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Uint8 memory[STACK_DEPTH];
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Uint8 mptr, sptr;
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Uint8 stack[STACK_DEPTH];
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Uint8 address[STACK_DEPTH];
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} Computer;
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void
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setflag(Computer *cpu, char flag, int b)
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{
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if(b)
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cpu->status |= flag;
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else
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cpu->status &= (~flag);
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}
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int
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getflag(Computer *cpu, char flag)
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{
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return cpu->status & flag;
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}
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void
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echo(Uint8 *s, Uint8 len, char *name)
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{
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int i;
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printf("%s\n", name);
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for(i = 0; i < len; ++i) {
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if(i % 16 == 0)
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printf("\n");
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printf("%02x ", s[i]);
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}
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printf("\n\n");
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}
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void
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op_push(Uint8 *s, Uint8 *ptr, Uint8 v)
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{
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s[*ptr] = v;
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(*ptr) += 1;
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}
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void
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op_pop(Uint8 *s, Uint8 *ptr)
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{
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s[*ptr--] = 0x00;
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}
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void
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reset(Computer *cpu)
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{
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int i;
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cpu->status = 0x00;
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cpu->counter = 0x00;
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cpu->mptr = 0x00;
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cpu->sptr = 0x00;
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cpu->literal = 0x00;
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for(i = 0; i < 256; i++)
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cpu->stack[i] = 0x00;
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}
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int
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error(char *name)
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{
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printf("Error: %s\n", name);
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return 0;
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}
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void
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load(Computer *cpu, FILE *f)
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{
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fread(cpu->memory, sizeof(cpu->memory), 1, f);
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}
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void
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eval(Computer *cpu)
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{
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Uint8 instr = cpu->memory[cpu->mptr++];
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if(cpu->literal > 0) {
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printf("push: %02x[%d](%d)\n", instr, cpu->literal, cpu->sptr);
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op_push(cpu->stack, &cpu->sptr, instr);
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cpu->literal--;
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return;
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}
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switch(instr) {
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case 0x0: setflag(cpu, FLAG_HALT, 1); break;
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case 0x1: cpu->literal += 4; break;
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default: printf("Unknown instruction: #%02x\n", instr);
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}
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}
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void
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run(Computer *cpu)
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{
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int i;
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while((cpu->status & FLAG_HALT) == 0)
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eval(cpu);
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/* debug */
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printf("ended @ %d | ", cpu->counter);
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for(i = 0; i < 4; i++)
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printf("%d-", (cpu->status & (1 << i)) != 0);
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printf("\n\n");
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}
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int
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main(int argc, char *argv[])
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{
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FILE *f;
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Computer cpu;
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if(argc < 2)
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return error("No input.");
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if(!(f = fopen(argv[1], "rb")))
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return error("Missing input.");
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reset(&cpu);
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load(&cpu, f);
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run(&cpu);
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/* print result */
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echo(cpu.stack, 0x40, "stack");
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echo(cpu.memory, 0x40, "memory");
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return 0;
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}
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