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Diffstat (limited to 'src/upb_varint.h')
| -rw-r--r-- | src/upb_varint.h | 142 |
1 files changed, 0 insertions, 142 deletions
diff --git a/src/upb_varint.h b/src/upb_varint.h deleted file mode 100644 index 87fca2b..0000000 --- a/src/upb_varint.h +++ /dev/null @@ -1,142 +0,0 @@ -/* - * upb - a minimalist implementation of protocol buffers. - * - * Copyright (c) 2011 Google Inc. See LICENSE for details. - * Author: Josh Haberman <jhaberman@gmail.com> - * - * A number of routines for varint manipulation (we keep them all around to - * have multiple approaches available for benchmarking). - */ - -#ifndef UPB_VARINT_DECODER_H_ -#define UPB_VARINT_DECODER_H_ - -#include "upb.h" -#include <stdint.h> -#include <string.h> - -#ifdef __cplusplus -extern "C" { -#endif - -/* Decoding *******************************************************************/ - -// All decoding functions return this struct by value. -typedef struct { - const char *p; // NULL if the varint was unterminated. - uint64_t val; -} upb_decoderet; - -// A basic branch-based decoder, uses 32-bit values to get good performance -// on 32-bit architectures (but performs well on 64-bits also). -INLINE upb_decoderet upb_vdecode_branch32(const char *p) { - upb_decoderet r = {NULL, 0}; - uint32_t low, high = 0; - uint32_t b; - b = *(p++); low = (b & 0x7f) ; if(!(b & 0x80)) goto done; - b = *(p++); low |= (b & 0x7f) << 7; if(!(b & 0x80)) goto done; - b = *(p++); low |= (b & 0x7f) << 14; if(!(b & 0x80)) goto done; - b = *(p++); low |= (b & 0x7f) << 21; if(!(b & 0x80)) goto done; - b = *(p++); low |= (b & 0x7f) << 28; - high = (b & 0x7f) >> 4; if(!(b & 0x80)) goto done; - b = *(p++); high |= (b & 0x7f) << 3; if(!(b & 0x80)) goto done; - b = *(p++); high |= (b & 0x7f) << 10; if(!(b & 0x80)) goto done; - b = *(p++); high |= (b & 0x7f) << 17; if(!(b & 0x80)) goto done; - b = *(p++); high |= (b & 0x7f) << 24; if(!(b & 0x80)) goto done; - b = *(p++); high |= (b & 0x7f) << 31; if(!(b & 0x80)) goto done; - return r; - -done: - r.val = ((uint64_t)high << 32) | low; - r.p = p; - return r; -} - -// Like the previous, but uses 64-bit values. -INLINE upb_decoderet upb_vdecode_branch64(const char *p) { - uint64_t val; - uint64_t b; - upb_decoderet r = {(void*)0, 0}; - b = *(p++); val = (b & 0x7f) ; if(!(b & 0x80)) goto done; - b = *(p++); val |= (b & 0x7f) << 7; if(!(b & 0x80)) goto done; - b = *(p++); val |= (b & 0x7f) << 14; if(!(b & 0x80)) goto done; - b = *(p++); val |= (b & 0x7f) << 21; if(!(b & 0x80)) goto done; - b = *(p++); val |= (b & 0x7f) << 28; if(!(b & 0x80)) goto done; - b = *(p++); val |= (b & 0x7f) << 35; if(!(b & 0x80)) goto done; - b = *(p++); val |= (b & 0x7f) << 42; if(!(b & 0x80)) goto done; - b = *(p++); val |= (b & 0x7f) << 49; if(!(b & 0x80)) goto done; - b = *(p++); val |= (b & 0x7f) << 56; if(!(b & 0x80)) goto done; - b = *(p++); val |= (b & 0x7f) << 63; if(!(b & 0x80)) goto done; - return r; - -done: - r.val = val; - r.p = p; - return r; -} - -// Decodes a varint of at most 8 bytes without branching (except for error). -upb_decoderet upb_vdecode_max8_wright(upb_decoderet r); - -// Another implementation of the previous. -upb_decoderet upb_vdecode_max8_massimino(upb_decoderet r); - -// Template for a function that checks the first two bytes with branching -// and dispatches 2-10 bytes with a separate function. -#define UPB_VARINT_DECODER_CHECK2(name, decode_max8_function) \ -INLINE upb_decoderet upb_vdecode_check2_ ## name(const char *_p) { \ - uint8_t *p = (uint8_t*)_p; \ - if ((*p & 0x80) == 0) { upb_decoderet r = {_p + 1, *p & 0x7f}; return r; } \ - upb_decoderet r = {_p + 2, (*p & 0x7f) | ((*(p + 1) & 0x7f) << 7)}; \ - if ((*(p + 1) & 0x80) == 0) return r; \ - return decode_max8_function(r); \ -} - -UPB_VARINT_DECODER_CHECK2(wright, upb_vdecode_max8_wright); -UPB_VARINT_DECODER_CHECK2(massimino, upb_vdecode_max8_massimino); -#undef UPB_VARINT_DECODER_CHECK2 - -// Our canonical functions for decoding varints, based on the currently -// favored best-performing implementations. -INLINE upb_decoderet upb_vdecode_fast(const char *p) { - // Use nobranch2 on 64-bit, branch32 on 32-bit. - if (sizeof(long) == 8) - return upb_vdecode_check2_massimino(p); - else - return upb_vdecode_branch32(p); -} - -INLINE upb_decoderet upb_vdecode_max8_fast(upb_decoderet r) { - return upb_vdecode_max8_massimino(r); -} - - -/* Encoding *******************************************************************/ - -INLINE size_t upb_value_size(uint64_t val) { -#ifdef __GNUC__ - int high_bit = 63 - __builtin_clzll(val); // 0-based, undef if val == 0. -#else - int high_bit = 0; - uint64_t tmp = val; - while(tmp >>= 1) high_bit++; -#endif - return val == 0 ? 1 : high_bit / 8 + 1; -} - -// Encodes a 32-bit varint, *not* sign-extended. -INLINE uint64_t upb_vencode32(uint32_t val) { - uint64_t ret = 0; - for (int bitpos = 0; val; bitpos+=8, val >>=7) { - if (bitpos > 0) ret |= (1 << (bitpos-1)); - ret |= (val & 0x7f) << bitpos; - } - return ret; -} - - -#ifdef __cplusplus -} /* extern "C" */ -#endif - -#endif /* UPB_VARINT_DECODER_H_ */ |