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