Dasm.cc

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#include "Dasm.hh"
#include "DasmTables.hh"
#include "MSXCPUInterface.hh"
#include "strCat.hh"
 
namespace openmsx {
 
static constexpr char sign(unsigned char a)
{
        return (a & 128) ? '-' : '+';
}
 
static constexpr int abs(unsigned char a)
{
        return (a & 128) ? (256 - a) : a;
}
 
unsigned dasm(const MSXCPUInterface& interf, word pc, byte buf[4],
              std::string& dest, EmuTime::param time)
{
        const char* r = nullptr;
 
        buf[0] = interf.peekMem(pc, time);
        auto [s, i] = [&]() -> std::pair<const char*, unsigned> {
                switch (buf[0]) {
                        case 0xCB:
                                buf[1] = interf.peekMem(pc + 1, time);
                                return {mnemonic_cb[buf[1]], 2};
                        case 0xED:
                                buf[1] = interf.peekMem(pc + 1, time);
                                return {mnemonic_ed[buf[1]], 2};
                        case 0xDD:
                        case 0xFD:
                                r = (buf[0] == 0xDD) ? "ix" : "iy";
                                buf[1] = interf.peekMem(pc + 1, time);
                                if (buf[1] != 0xcb) {
                                        return {mnemonic_xx[buf[1]], 2};
                                } else {
                                        buf[2] = interf.peekMem(pc + 2, time);
                                        buf[3] = interf.peekMem(pc + 3, time);
                                        return {mnemonic_xx_cb[buf[3]], 4};
                                }
                        default:
                                return {mnemonic_main[buf[0]], 1};
                }
        }();
 
        for (int j = 0; s[j]; ++j) {
                switch (s[j]) {
                case 'B':
                        buf[i] = interf.peekMem(pc + i, time);
                        strAppend(dest, '#', hex_string<2>(
                                static_cast<uint16_t>(buf[i])));
                        i += 1;
                        break;
                case 'R':
                        buf[i] = interf.peekMem(pc + i, time);
                        strAppend(dest, '#', hex_string<4>(
                                pc + 2 + static_cast<int8_t>(buf[i])));
                        i += 1;
                        break;
                case 'W':
                        buf[i + 0] = interf.peekMem(pc + i + 0, time);
                        buf[i + 1] = interf.peekMem(pc + i + 1, time);
                        strAppend(dest, '#', hex_string<4>(buf[i] + buf[i + 1] * 256));
                        i += 2;
                        break;
                case 'X':
                        buf[i] = interf.peekMem(pc + i, time);
                        strAppend(dest, '(', r, sign(buf[i]), '#',
                             hex_string<2>(abs(buf[i])), ')');
                        i += 1;
                        break;
                case 'Y':
                        strAppend(dest, r, sign(buf[2]), '#', hex_string<2>(abs(buf[2])));
                        break;
                case 'I':
                        dest += r;
                        break;
                case '!':
                        dest = strCat("db     #ED,#", hex_string<2>(buf[1]),
                                      "     ");
                        return 2;
                case '@':
                        dest = strCat("db     #", hex_string<2>(buf[0]),
                                      "         ");
                        return 1;
                case '#':
                        dest = strCat("db     #", hex_string<2>(buf[0]),
                                      ",#CB,#", hex_string<2>(buf[2]),
                                      ' ');
                        return 2;
                case ' ': {
                        dest.resize(7, ' ');
                        break;
                }
                default:
                        dest += s[j];
                        break;
                }
        }
        dest.resize(19, ' ');
        return i;
}
 
} // namespace openmsx