mirror of https://gitlab.freedesktop.org/mesa/mesa
113 lines
3.5 KiB
C
113 lines
3.5 KiB
C
/*
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* Copyright © 2018 Intel Corporation
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*
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* Permission is hereby granted, free of charge, to any person obtaining a
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* copy of this software and associated documentation files (the "Software"),
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* to deal in the Software without restriction, including without limitation
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* the rights to use, copy, modify, merge, publish, distribute, sublicense,
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* and/or sell copies of the Software, and to permit persons to whom the
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* Software is furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice (including the next
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* paragraph) shall be included in all copies or substantial portions of the
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* Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
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* IN THE SOFTWARE.
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*/
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#ifndef UTIL_BIGMATH_H
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#define UTIL_BIGMATH_H
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#include "macros.h"
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#include <assert.h>
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#include <stdint.h>
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#include <string.h>
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static inline bool
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_ubm_add_u32arr(uint32_t *dst, unsigned dst_len,
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uint32_t *a, unsigned a_len,
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uint32_t *b, unsigned b_len)
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{
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uint32_t carry = 0;
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for (unsigned i = 0; i < dst_len; i++) {
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uint64_t sum = carry;
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if (i < a_len)
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sum += a[i];
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if (i < b_len)
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sum += b[i];
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dst[i] = sum;
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carry = sum >> 32;
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}
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/* Now compute overflow */
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for (unsigned i = dst_len; i < a_len; i++) {
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if (a[i])
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return true;
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}
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for (unsigned i = dst_len; i < b_len; i++) {
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if (b[i])
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return true;
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}
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return carry;
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}
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#define ubm_add_u32arr(dst, a, b) \
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_ubm_add_u32arr(dst, ARRAY_SIZE(dst), a, ARRAY_SIZE(a), b, ARRAY_SIZE(b))
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static inline bool
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_ubm_mul_u32arr(uint32_t *dst, unsigned dst_len,
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uint32_t *a, unsigned a_len,
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uint32_t *b, unsigned b_len)
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{
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memset(dst, 0, dst_len * sizeof(*dst));
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bool overflow = false;
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for (unsigned i = 0; i < a_len; i++) {
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uint32_t carry = 0;
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for (unsigned j = 0; j < b_len; j++) {
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/* The maximum values of a[i] and b[i] are UINT32_MAX so the maximum
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* value of tmp is UINT32_MAX * UINT32_MAX. The maximum value that
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* will fit in tmp is
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*
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* UINT64_MAX = UINT32_MAX << 32 + UINT32_MAX
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* = UINT32_MAX * (UINT32_MAX + 1) + UINT32_MAX
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* = UINT32_MAX * UINT32_MAX + 2 * UINT32_MAX
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*
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* so we're guaranteed that we can add in two more 32-bit values
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* without overflowing tmp.
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*/
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uint64_t tmp = (uint64_t)a[i] * (uint64_t)b[j];
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tmp += carry;
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if (i + j < dst_len) {
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tmp += dst[i + j];
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dst[i + j] = tmp;
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carry = tmp >> 32;
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} else {
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/* We're trying to write a value that doesn't fit */
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overflow = overflow || tmp > 0;
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break;
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}
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}
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if (i + b_len < dst_len)
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dst[i + b_len] = carry;
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else
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overflow = overflow || carry > 0;
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}
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return overflow;
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}
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#define ubm_mul_u32arr(dst, a, b) \
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_ubm_mul_u32arr(dst, ARRAY_SIZE(dst), a, ARRAY_SIZE(a), b, ARRAY_SIZE(b))
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#endif /* UTIL_BIGMATH_H */
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