// strtok / strtok_r — kept in their own translation unit so it can
// be built at -O0.  At -O2 (the default for everything else in
// runtime/build.sh) the W65816 backend miscompiles this code: the
// second `strtok(NULL, ...)` call returns NULL even though the save
// pointer is correctly populated by the first call.
//
// Investigation (#107):
//
// - Bisected to "appears at -O1 already, not -O2 specific".
// - NOT a single named optimization pass — `-O1 -mllvm -opt-bisect-limit=0`
//   (disable all named passes) still miscompiles, so it's something
//   gated only on `OptimizationLevel > None` in the codegen pipeline.
// - NOT inlining-related — `-O2 -fno-inline` still fails.
// - NOT regalloc-related — `-O2 -mllvm -regalloc=fast` still fails.
// - Tried 5 source-level rewrites (global ternary, explicit if/else,
//   strtok_r wrapper, hand-rolled inner loops without inSet helper,
//   unsigned-char throughout, combined-skip-walk single-loop with
//   `tok` sentinel).  Each shifts the bug to a slightly different
//   surface — the combined-loop form fixed the str==NULL second-call
//   path but broke consecutive-delim skipping with an off-by-one.
//
// The simplest reliable fix is to compile this TU at -O0 — see
// runtime/build.sh.  Same as the optnone-on-qsort workaround for #70:
// a known LLVM-mos backend fragility that we route around for now.

static char *gStrtokSave;


char *strtok_r(char *str, const char *delim, char **saveptr) {
    unsigned char *s;
    if (str != (char *)0) {
        s = (unsigned char *)str;
    } else {
        s = (unsigned char *)(*saveptr);
    }
    if (s == (unsigned char *)0) {
        return (char *)0;
    }
    const unsigned char *du = (const unsigned char *)delim;
    // Skip leading delimiters.
    for (;;) {
        unsigned char c = *s;
        if (c == 0) {
            *saveptr = (char *)0;
            return (char *)0;
        }
        const unsigned char *d = du;
        unsigned char isDelim = 0;
        while (*d != 0) {
            if (c == *d) {
                isDelim = 1;
                break;
            }
            d++;
        }
        if (!isDelim) {
            break;
        }
        s++;
    }
    unsigned char *tok = s;
    // Find next delimiter or NUL.
    for (;;) {
        unsigned char c = *s;
        if (c == 0) {
            *saveptr = (char *)0;
            return (char *)tok;
        }
        const unsigned char *d = du;
        unsigned char isDelim = 0;
        while (*d != 0) {
            if (c == *d) {
                isDelim = 1;
                break;
            }
            d++;
        }
        if (isDelim) {
            *s = 0;
            *saveptr = (char *)(s + 1);
            return (char *)tok;
        }
        s++;
    }
}


char *strtok(char *str, const char *delim) {
    return strtok_r(str, delim, &gStrtokSave);
}