1/* 2 * Common code for checksum implementations 3 * 4 * Copyright (c) 2020, Arm Limited. 5 * SPDX-License-Identifier: MIT OR Apache-2.0 WITH LLVM-exception 6 */ 7 8#ifndef CHKSUM_COMMON_H 9#define CHKSUM_COMMON_H 10 11#if __BYTE_ORDER__ != __ORDER_LITTLE_ENDIAN__ 12#error Only little endian supported 13#endif 14 15#include <limits.h> 16#include <stdbool.h> 17#include <stdint.h> 18#include <string.h> 19 20/* Assertions must be explicitly enabled */ 21#if WANT_ASSERT 22#undef NDEBUG 23#include <assert.h> 24#define Assert(exp) assert(exp) 25#else 26#define Assert(exp) (void) (exp) 27#endif 28 29#ifdef __GNUC__ 30#define likely(x) __builtin_expect(!!(x), 1) 31#define unlikely(x) __builtin_expect(!!(x), 0) 32#define may_alias __attribute__((__may_alias__)) 33#define always_inline __attribute__((always_inline)) 34#ifdef __clang__ 35#define no_unroll_loops 36#else 37#define no_unroll_loops __attribute__((optimize("no-unroll-loops"))) 38#endif 39#define bswap16(x) __builtin_bswap16((x)) 40#else 41#define likely(x) (x) 42#define unlikely(x) (x) 43#define may_alias 44#define always_inline 45#define no_unroll_loops 46#define bswap16(x) ((uint8_t)((x) >> 8) | ((uint8_t)(x) << 8)) 47#endif 48 49#define ALL_ONES ~UINT64_C(0) 50 51static inline 52uint64_t load64(const void *ptr) 53{ 54 /* GCC will optimise this to a normal load instruction */ 55 uint64_t v; 56 memcpy(&v, ptr, sizeof v); 57 return v; 58} 59 60static inline 61uint32_t load32(const void *ptr) 62{ 63 /* GCC will optimise this to a normal load instruction */ 64 uint32_t v; 65 memcpy(&v, ptr, sizeof v); 66 return v; 67} 68 69static inline 70uint16_t load16(const void *ptr) 71{ 72 /* GCC will optimise this to a normal load instruction */ 73 uint16_t v; 74 memcpy(&v, ptr, sizeof v); 75 return v; 76} 77 78/* slurp_small() is for small buffers, don't waste cycles on alignment */ 79no_unroll_loops 80always_inline 81static inline uint64_t 82slurp_small(const void *ptr, uint32_t nbytes) 83{ 84 const unsigned char *cptr = ptr; 85 uint64_t sum = 0; 86 while (nbytes >= 4) 87 { 88 sum += load32(cptr); 89 cptr += 4; 90 nbytes -= 4; 91 } 92 if (nbytes & 2) 93 { 94 sum += load16(cptr); 95 cptr += 2; 96 } 97 if (nbytes & 1) 98 { 99 sum += (uint8_t) *cptr; 100 } 101 return sum; 102} 103 104static inline const void * 105align_ptr(const void *ptr, size_t bytes) 106{ 107 return (void *) ((uintptr_t) ptr & -(uintptr_t) bytes); 108} 109 110always_inline 111static inline uint16_t 112fold_and_swap(uint64_t sum, bool swap) 113{ 114 /* Fold 64-bit sum to 32 bits */ 115 sum = (sum & 0xffffffff) + (sum >> 32); 116 sum = (sum & 0xffffffff) + (sum >> 32); 117 Assert(sum == (uint32_t) sum); 118 119 /* Fold 32-bit sum to 16 bits */ 120 sum = (sum & 0xffff) + (sum >> 16); 121 sum = (sum & 0xffff) + (sum >> 16); 122 Assert(sum == (uint16_t) sum); 123 124 if (unlikely(swap)) /* Odd base pointer is unexpected */ 125 { 126 sum = bswap16(sum); 127 } 128 129 return (uint16_t) sum; 130} 131 132#endif 133