Research problems

[ascherer]

At various places in the MMIX sources, Don Knuth asks the interested reader to make significant changes for advanced system features:

• Unicode support using wchar for Char (MMOTYPE§27, MMIXAL§§{7,30})
• octa as single 64-bit integer, e.g., using uint64_t instead of the current struct with two tetras (ILP64 interface) (MMIX-ARITH§1); see GIMMIX for ideas
• Graphical interface (MMIX-SIM§1)
• Implement MMIXAL-style expressions for interactive debugging (MMIX-SIM§24)
• Simulate a B-Cache (MMIX-PIPE§217)
• Can count_bits, byte_diff, or wyde_diff be done with fewer operations? (MMIX-AITH§28)
• Check buffer overflow in MMIXAL§§(74,75,77,79): done.
• …

Time permitting, I'll try to look up the relevant sections in the codes.

[ascherer]

Copilot suggests these changes for mmotype.w:

#include <wchar.h>

// Change to wide character buffer
wchar_t sym_buf[sym_length_max];
wchar_t *sym_ptr;

// Example function update for reading wide characters
wchar_t read_wchar() {
    wchar_t wc;
    if (fgetwc(mmo_file, &wc) != 1) {
        fprintf(stderr, "Unexpected end of file after %d characters!\n", count);
        exit(-3);
    }
    return wc;
}

// Update the print function
void print_stab() {
    register int m = read_byte();
    register wchar_t c;
    if (m & 0x40) print_stab();
    if (m & 0x2f) {
        c = read_wchar();
        *sym_ptr++ = c;
        if (sym_ptr == &sym_buf[sym_length_max]) {
            fwprintf(stderr, L"Oops, the symbol is too long!\n");
            exit(-7);
        }
        if (m & 0xf) {
            // Update printing logic for wide characters
            *sym_ptr = L'\0';
            fwprintf(stdout, L"    %ls (%d)\n", sym_buf, m & 0xf);
        }
        if (m & 0x20) print_stab();
        sym_ptr--;
    }
    if (m & 0x10) print_stab();
}