gloam 0.4.4

Loader generator for Vulkan, OpenGL, OpenGL ES, EGL, GLX, and WGL
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{% if fs.extensions | length > 0 %}
#ifndef GLOAM_IMPL_HASHSEARCH_C_
#define GLOAM_IMPL_HASHSEARCH_C_

/* gloam_sort_hashes — in-place Shellsort on a uint64_t array.
 *
 * Ciura (2001) gap sequence.  Gaps larger than n are skipped at runtime so
 * small arrays (< 10 extensions) take only a couple of passes.  No heap
 * allocation; code size is ~80 bytes on x86-64.
 */
GLOAM_NO_INLINE static void gloam_sort_hashes(uint64_t *a, size_t n)
{
    static const size_t kGaps[] = { 701, 301, 132, 57, 23, 10, 4, 1 };
    size_t gi = 0;
    if (!a || n < 2) return;
    /* Skip gaps that are larger than the array. */
    while (gi < GLOAM_ARRAYSIZE(kGaps) && kGaps[gi] >= n) ++gi;
    for (; gi < GLOAM_ARRAYSIZE(kGaps); ++gi) {
        size_t gap = kGaps[gi], i;
        for (i = gap; i < n; ++i) {
            uint64_t v = a[i];
            size_t j = i;
            while (j >= gap && a[j - gap] > v) {
                a[j] = a[j - gap];
                j -= gap;
            }
            a[j] = v;
        }
    }
}

/* gloam_hash_search — binary search for `target` in a sorted uint64_t array.
 * Returns 1 if found, 0 otherwise.
 */
GLOAM_NO_INLINE static int gloam_hash_search(const uint64_t *arr, uint32_t size, uint64_t target)
{
    int32_t lo = 0, hi = (int32_t)size - 1;
    while (lo <= hi) {
        int32_t mid = lo + (hi - lo) / 2;
        if (arr[mid] == target) return 1;
        if (arr[mid] < target)  lo = mid + 1;
        else                    hi = mid - 1;
    }
    return 0;
}

/* gloam_hash_string — hash a NUL-terminated string with XXH3-64.
 * The same algorithm is used at generator time to pre-bake kExtHashes[],
 * guaranteeing that driver-reported names and the embedded table match.
 */
GLOAM_NO_INLINE static uint64_t gloam_hash_string(const char *str, size_t length)
{
    return XXH3_64bits(str, length);
}

/* ---- Extension string tokenizer ------------------------------------------
   Two-pass tokenize-and-hash for space-separated extension strings (GL, EGL,
   GLX, WGL).  First pass counts tokens, second pass hashes them.  Result is
   sorted for binary search in find_extensions. */
GLOAM_NO_INLINE static int gloam_hash_ext_string(const char *ext_str, uint64_t **out_exts, uint32_t *out_num_exts)
{
    const char *cur, *next;
    uint64_t *exts = NULL;
    uint32_t num_exts = 0, j;

    for (j = 0; j < 2; ++j) {
        num_exts = 0;
        cur  = ext_str;
        next = cur + strcspn(cur, " ");
        while (1) {
            size_t len;
            cur += strspn(cur, " ");
            if (!cur[0])
                break;
            len = (size_t)(next - cur);
            if (exts)
                exts[num_exts] = gloam_hash_string(cur, len);
            ++num_exts;
            cur  = next + strspn(next, " ");
            next = cur  + strcspn(cur,  " ");
        }
        if (!exts) {
            exts = (uint64_t *)calloc(num_exts, sizeof(uint64_t));
            if (!exts)
                return 0;
        }
    }

    gloam_sort_hashes(exts, num_exts);
    *out_exts     = exts;
    *out_num_exts = num_exts;
    return 1;
}
#endif /* GLOAM_IMPL_HASHSEARCH_C_ */
{% endif %}