view emulator/emu.c @ 25:45340c2a38c5

tidier and less buggier

/* emu.c
 * emuulation start up and fetch/decode/execute loop */
#include <stdio.h>
#include <string.h>
#include "mem.h"
#include "iset.h"

/* instruction table */
void (*iset[256])(void) = {
    NOP, NOP, NOP, NOP, NOP, NOP, NOP, NOP,
    SET, CLR, SET, CLR, SET, CLR, CPL, CPL,
    XCSD, SFA, LAF, MOV, MOV, MOV, MOV, MOV,
    MOV, MOV, MOV, MOV, MOV, MOV, MOV, MOV,
    MOV, MOV, MOV, MOV, MOV, MOV, MOV, MOV,
    MOV, MOV, MOV, MOV, MOV, MOV, MOV, MOV,
    MOV, MOV, MOV, MOV, MOV, MOV, MOV, MOV,
    MOV, MOV, MOV, MOV, MOV, MOV, MOV, MOV,
    MOV, MOV, MOV, MOV, MOV, MOV, MOV, MOV,
    MOV, MOV, MOV, MOV, MOV, MOV, MOV, MOV,
    MOV, MOV, MOV, MOV, MOV, MOV, MOV, MOV,
    MOV, MOV, MOV, MOV, MOV, MOV, MOV, MOV,
    MOV, MOV, MOV, MOV, MOV, MOV, MOV, MOV,
    MOV, MOV, MOV, MOV, MOV, MOV, MOV, MOV,
    MOV, MOV, MOV, MOV, MOV, MOV, MOV, MOV,
    MOV, MOV, MOV, MOV, MOV, MOV, MOV, MOV,
    ANL, ANL, ANL, ANL, ANL, ANL, ANL, ANL,
    ORL, ORL, ORL, ORL, ORL, ORL, ORL, ORL,
    XRL, XRL, XRL, XRL, XRL, XRL, XRL, XRL,
    RL, RLC, RR, RRC, INC, DEC, INC, DEC,
    ADD, ADD, ADD, ADD, ADD, ADD, ADD, ADD,
    ADDC, ADDC, ADDC, ADDC, ADDC, ADDC, ADDC, ADDC,
    SUB, SUB, SUB, SUB, SUB, SUB, SUB, SUB,
    SUBB, SUBB, SUBB, SUBB, SUBB, SUBB, SUBB, SUBB,
    PJMP, PJMP, PJMP, PJMP, PJMP, PJMP, PJMP, PJMP,
    PCALL, PCALL, PCALL, PCALL, PCALL, PCALL, PCALL, PCALL,
    DJNZ, DJNZ, DJNZ, DJNZ, CJNE, CJNE, CJNE, CJNE,
    LJMP, LCALL, RET, RETI, SJMP, JMP, JMP, CJNE,
    JZ, JNZ, JC, JNC, JPO, JPE, JS, JNS,
    PUSH, PUSH, PUSH, PUSH, PUSH, PUSH, PUSH, PUSH,
    POP, POP, POP, POP, POP, POP, POP, POP,
    MUL, DIV, DA, NOP, IN, OUT, INT, HLT
};

void
boot(void) {
    /* set everything to zero */
    memset(&registers, 0, sizeof(registers));
    memset(&memory, 0, sizeof(memory));

    /* load program from stdin
     * c must be signed int since EOF is -1 on linux */
    WIDE i = 0;
    signed short int c = getchar();
    for(i ; i < 0x10000 ; i++) {
        if (c == EOF) { break; }
        memory[i] = c;
        c = getchar();
    }
}

void 
step(void) {
    op = fetch();
    (*iset[op])();
}

void 
main(void) {
    boot();
    for (;;) { 
        step();
    }
}