util/idalloc: add util_idalloc_alloc_range
v2: fixed infinite loop (Pierre-Eric) Reviewed-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com> (v1) Reviewed-by: Marek Olšák <marek.olsak@amd.com> (v2) Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/11493>
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@ -85,6 +85,62 @@ util_idalloc_alloc(struct util_idalloc *buf)
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return num_elements * 32;
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}
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static unsigned
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find_free_block(struct util_idalloc *buf, unsigned start)
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{
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for (unsigned i = start; i < buf->num_elements; i++) {
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if (!buf->data[i])
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return i;
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}
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return buf->num_elements;
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}
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/* Allocate a range of consecutive IDs. Return the first ID. */
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unsigned
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util_idalloc_alloc_range(struct util_idalloc *buf, unsigned num)
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{
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if (num == 1)
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return util_idalloc_alloc(buf);
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unsigned num_alloc = DIV_ROUND_UP(num, 32);
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unsigned num_elements = buf->num_elements;
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unsigned base = find_free_block(buf, buf->lowest_free_idx);
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while (1) {
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unsigned i;
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for (i = base;
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i < num_elements && i - base < num_alloc && !buf->data[i]; i++);
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if (i - base == num_alloc)
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goto ret; /* found */
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if (i == num_elements)
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break; /* not found */
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/* continue searching */
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base = !buf->data[i] ? i : i + 1;
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}
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/* No slots available, allocate more. */
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util_idalloc_resize(buf, num_elements * 2 + num_alloc);
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ret:
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/* Mark the bits as used. */
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for (unsigned i = base; i < base + num_alloc - (num % 32 != 0); i++)
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buf->data[i] = 0xffffffff;
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if (num % 32 != 0)
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buf->data[base + num_alloc - 1] |= BITFIELD_MASK(num % 32);
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if (buf->lowest_free_idx == base)
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buf->lowest_free_idx = base + num / 32;
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/* Validate this algorithm. */
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for (unsigned i = 0; i < num; i++)
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assert(util_idalloc_exists(buf, base * 32 + i));
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return base * 32;
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}
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void
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util_idalloc_free(struct util_idalloc *buf, unsigned id)
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{
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@ -58,6 +58,9 @@ util_idalloc_fini(struct util_idalloc *buf);
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unsigned
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util_idalloc_alloc(struct util_idalloc *buf);
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unsigned
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util_idalloc_alloc_range(struct util_idalloc *buf, unsigned num);
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void
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util_idalloc_free(struct util_idalloc *buf, unsigned id);
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