disasm.cpp

#include <stdint.h>
#include <stdio.h>
#include <array>
#include <Arduino.h>
#include "avr11.h"
#include "kb11.h"
#include "unibus.h"

extern KB11 cpu;

constexpr std::array<const char *, 8> rs = {"R0", "R1", "R2", "R3", "R4", "R5", "SP", "PC"};

struct D {
    uint16_t mask;
    uint16_t ins;
    const char *msg;
    uint8_t flag;
    bool b;
};

enum { DD = 1 << 1, S = 1 << 2, RR = 1 << 3, O = 1 << 4, N = 1 << 5 };

extern KB11 cpu;

constexpr D disamtable[] = {
    {0177777, 0000001, "WAIT", 0, false},
    {0177777, 0000002, "RTI", 0, false},
    {0177777, 0000003, "BPT", 0, false},
    {0177777, 0000004, "IOT", 0, false},
    {0177777, 0000005, "RESET", 0, false},
    {0177777, 0000006, "RTT", 0, false},
    {0177777, 0000007, "MFPT", 0, false},

    {0177700, 0000100, "JMP", DD, false},
    {0177770, 0000200, "RTS", RR, false},
    {0177700, 0000300, "SWAB", DD, false},

    {0177700, 0006400, "MARK", N, false},
    {0177700, 0006500, "MFPI", DD, false},
    {0177700, 0006600, "MTPI", DD, false},
    {0177700, 0006700, "SXT", DD, false},

    {0177400, 0104000, "EMT", N, false},
    {0177400, 0104400, "TRAP", N, false},
    {0177400, 0100000, "BPL", O, false},
    {0177400, 0100400, "BMI", O, false},
    {0177400, 0101000, "BHI", O, false},
    {0177400, 0101400, "BLOS", O, false},
    {0177400, 0102000, "BVC", O, false},
    {0177400, 0102400, "BVS", O, false},
    {0177400, 0103000, "BCC", O, false},
    {0177400, 0103400, "BCS", O, false},
    {0177400, 0000400, "BR", O, false},
    {0177400, 0001000, "BNE", O, false},
    {0177400, 0001400, "BEQ", O, false},
    {0177400, 0002000, "BGE", O, false},
    {0177400, 0002400, "BLT", O, false},
    {0177400, 0003000, "BGT", O, false},
    {0177400, 0003400, "BLE", O, false},

    {0177000, 0004000, "JSR", RR | DD, false},
    {0177000, 0070000, "MUL", RR | DD, false},
    {0177000, 0071000, "DIV", RR | DD, false},
    {0177000, 0072000, "ASH", RR | DD, false},
    {0177000, 0073000, "ASHC", RR | DD, false},
    {0177000, 0077000, "SOB", RR | O, false},
    {0170000, 0060000, "ADD", S | DD, false},
    {0170000, 0160000, "SUB", S | DD, false},

    {0077700, 0005000, "CLR", DD, true},
    {0077700, 0005100, "COM", DD, true},
    {0077700, 0005200, "INC", DD, true},
    {0077700, 0005300, "DEC", DD, true},
    {0077700, 0005400, "NEG", DD, true},
    {0077700, 0005500, "ADC", DD, true},
    {0077700, 0005600, "SBC", DD, true},
    {0077700, 0005700, "TST", DD, true},
    {0077700, 0006000, "ROR", DD, true},
    {0077700, 0006100, "ROL", DD, true},
    {0077700, 0006200, "ASR", DD, true},
    {0077700, 0006300, "ASL", DD, true},

    {0070000, 0010000, "MOV", S | DD, true},
    {0070000, 0020000, "CMP", S | DD, true},
    {0070000, 0030000, "BIT", S | DD, true},
    {0070000, 0040000, "BIC", S | DD, true},
    {0070000, 0050000, "BIS", S | DD, true},
    {0000000, 0000001, "HALT", 0, false}, // fake instruction so HALT is left in l
    {0, 0, "", 0, false},
};

void disasmaddr(uint16_t m, uint32_t a) {
    if (m & 7) {
        switch (m) {
        case 027:
            a += 2;
            Serial.printf("$%06o", cpu.read16(a));
            return;
        case 037:
            a += 2;
            Serial.printf("*%06o", cpu.read16(a));
            return;
        case 067:
            a += 2;
            Serial.printf("*%06o", (a + 2 + (cpu.read16(a))) & 0xFFFF);
            return;
        case 077:
            Serial.printf("**%06o", (a + 2 + (cpu.read16(a))) & 0xFFFF);
            return;
        }
    }

    switch (m & 070) {
    case 000:
        Serial.printf("%s", rs[m & 7]);
        break;
    case 010:
        Serial.printf("(%s)", rs[m & 7]);
        break;
    case 020:
        Serial.printf("(%s)+", rs[m & 7]);
        break;
    case 030:
        Serial.printf("*(%s)+", rs[m & 7]);
        break;
    case 040:
        Serial.printf("-(%s)", rs[m & 7]);
        break;
    case 050:
        Serial.printf("*-(%s)", rs[m & 7]);
        break;
    case 060:
        a += 2;
        Serial.printf("%06o (%s)", cpu.read16(a), rs[m & 7]);
        break;
    case 070:
        a += 2;
        Serial.printf("*%06o (%s)", cpu.read16(a), rs[m & 7]);
        break;
    }
}

void disasm(uint32_t a) {
    const uint16_t ins = cpu.read16(a);

    D l = {0, 0, "", 0, false};
    for (uint16_t i = 0; disamtable[i].ins; i++) {
        l = disamtable[i];
        if ((ins & l.mask) == l.ins) {
            break;
        }
    }
    if (l.ins == 0) {
        Serial.printf("???");
        return;
    }

    Serial.printf("%s", l.msg);
    if (l.b && (ins & 0100000)) {
        Serial.printf("B");
    }
    const uint16_t s = (ins & 07700) >> 6;
    const uint16_t d = ins & 077;
    uint16_t o = ins & 0377;
    switch (l.flag) {
    case S | DD:
        Serial.printf(" ");
        disasmaddr(s, a);
        Serial.printf(",");
        [[fallthrough]];
    case DD:
        Serial.printf(" ");
        disasmaddr(d, a);
        break;
    case RR | O:
        Serial.printf(" %s,", rs[(ins & 0700) >> 6]);
        o &= 077;
        [[fallthrough]];
    case O:
        if (o & 0x80) {
            Serial.printf(" -%03o", (2 * ((0xFF ^ o) + 1)));
        } else {
            Serial.printf(" +%03o", (2 * o));
        };
        break;
    case RR | DD:
        Serial.printf(" %s, ", rs[(ins & 0700) >> 6]);
        disasmaddr(d, a);
        [[fallthrough]];
    case RR:
        Serial.printf(" %s", rs[ins & 7]);
    }
}