asm_chip8.c

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// SPDX-FileCopyrightText: 2017-2018 maijin <maijin21@gmail.com>
// SPDX-License-Identifier: LGPL-3.0-only
 
#include <rz_asm.h>
#include <rz_lib.h>
 
static int disassemble(RzAsm *a, RzAsmOp *op, const ut8 *b, int l) {
    ut16 opcode = rz_read_be16(b);
    uint8_t x = (opcode >> 8) & 0x0F;
    uint8_t y = (opcode >> 4) & 0x0F;
    uint8_t nibble = opcode & 0x0F;
    uint16_t nnn = opcode & 0x0FFF;
    uint8_t kk = opcode & 0xFF;
    const char *buf_asm = "invalid";
    switch (opcode & 0xF000) {
    case 0x0000:
        if (opcode == 0x00E0) {
            buf_asm = "cls";
        } else if (opcode == 0x00EE) {
            buf_asm = "ret";
        } else if ((opcode & 0xFFF0) == 0x00C0) {
            buf_asm = sdb_fmt("scd 0x%01x", nibble);
        } else if (opcode == 0x00FB) {
            buf_asm = "scr";
        } else if (opcode == 0x00FC) {
            buf_asm = "scl";
        } else if (opcode == 0x00FD) {
            buf_asm = "exit";
        } else if (opcode == 0x00FE) {
            buf_asm = "low";
        } else if (opcode == 0x00FF) {
            buf_asm = "high";
        }
        break;
    case 0x1000: buf_asm = sdb_fmt("jp 0x%03x", nnn); break;
    case 0x2000: buf_asm = sdb_fmt("call 0x%03x", nnn); break;
    case 0x3000: buf_asm = sdb_fmt("se v%1x, 0x%02x", x, kk); break;
    case 0x4000: buf_asm = sdb_fmt("sne v%1x, 0x%02x", x, kk); break;
    case 0x5000: buf_asm = sdb_fmt("se v%1x, v%1x", x, y); break;
    case 0x6000: buf_asm = sdb_fmt("ld v%1x, 0x%02x", x, kk); break;
    case 0x7000: buf_asm = sdb_fmt("add v%1x, 0x%02x", x, kk); break;
    case 0x8000: {
        switch (nibble) {
        case 0x0: buf_asm = sdb_fmt("ld v%1x, v%1x", x, y); break;
        case 0x1: buf_asm = sdb_fmt("or v%1x, v%1x", x, y); break;
        case 0x2: buf_asm = sdb_fmt("and v%1x, v%1x", x, y); break;
        case 0x3: buf_asm = sdb_fmt("xor v%1x, v%1x", x, y); break;
        case 0x4: buf_asm = sdb_fmt("add v%1x, v%1x", x, y); break;
        case 0x5: buf_asm = sdb_fmt("sub v%1x, v%1x", x, y); break;
        case 0x6: buf_asm = sdb_fmt("shr v%1x, v%1x", x, y); break;
        case 0x7: buf_asm = sdb_fmt("subn v%1x, v%1x", x, y); break;
        case 0xE: buf_asm = sdb_fmt("shl v%1x, v%1x", x, y); break;
        }
    } break;
    case 0x9000: buf_asm = sdb_fmt("sne v%1x, v%1x", x, y); break;
    case 0xA000: buf_asm = sdb_fmt("ld i, 0x%03x", nnn); break;
    case 0xB000: buf_asm = sdb_fmt("jp v0, 0x%03x", nnn); break;
    case 0xC000: buf_asm = sdb_fmt("rnd v%1x, 0x%02x", x, kk); break;
    case 0xD000: buf_asm = sdb_fmt("drw v%1x, v%1x, 0x%01x", x, y, nibble); break;
    case 0xE000: {
        if (kk == 0x9E) {
            buf_asm = sdb_fmt("skp v%1x", x);
        } else if (kk == 0xA1) {
            buf_asm = sdb_fmt("sknp v%1x", x);
        }
    } break;
    case 0xF000: {
        switch (kk) {
        case 0x07: buf_asm = sdb_fmt("ld v%1x, dt", x); break;
        case 0x0A: buf_asm = sdb_fmt("ld v%1x, k", x); break;
        case 0x15: buf_asm = sdb_fmt("ld dt, v%1x", x); break;
        case 0x18: buf_asm = sdb_fmt("ld st, v%1x", x); break;
        case 0x1E: buf_asm = sdb_fmt("add i, v%1x", x); break;
        case 0x29: buf_asm = sdb_fmt("ld f, v%1x", x); break;
        case 0x33: buf_asm = sdb_fmt("ld b, v%1x", x); break;
        case 0x55: buf_asm = sdb_fmt("ld [i], v%1x", x); break;
        case 0x65: buf_asm = sdb_fmt("ld v%1x, [i]", x); break;
        case 0x30: buf_asm = sdb_fmt("ld hf, v%1x", x); break;
        case 0x75: buf_asm = sdb_fmt("ld r, v%1x", x); break;
        case 0x85: buf_asm = sdb_fmt("ld v%1x, r", x); break;
        }
    } break;
    }
    rz_strbuf_set(&op->buf_asm, buf_asm);
    op->size = 2;
    return op->size;
}
 
RzAsmPlugin rz_asm_plugin_chip8 = {
    .name = "chip8",
    .arch = "chip8",
    .license = "LGPL3",
    .bits = 32,
    .desc = "Chip8 disassembler",
    .disassemble = &disassemble,
};
 
#ifndef RZ_PLUGIN_INCORE
RZ_API RzLibStruct rizin_plugin = {
    .type = RZ_LIB_TYPE_ASM,
    .data = &rz_asm_plugin_chip8,
    .version = RZ_VERSION
};
#endif