1 // Protocol Buffers - Google's data interchange format
2 // Copyright 2023 Google LLC. All rights reserved.
3 //
4 // Use of this source code is governed by a BSD-style
5 // license that can be found in the LICENSE file or at
6 // https://developers.google.com/open-source/licenses/bsd
7
8 #ifndef UPB_MINI_DESCRIPTOR_INTERNAL_BASE92_H_
9 #define UPB_MINI_DESCRIPTOR_INTERNAL_BASE92_H_
10
11 #include <stdint.h>
12
13 #include "upb/base/internal/log2.h"
14
15 // Must be last.
16 #include "upb/port/def.inc"
17
18 #ifdef __cplusplus
19 extern "C" {
20 #endif
21
_upb_ToBase92(int8_t ch)22 UPB_INLINE char _upb_ToBase92(int8_t ch) {
23 extern const char _kUpb_ToBase92[];
24 UPB_ASSERT(0 <= ch && ch < 92);
25 return _kUpb_ToBase92[ch];
26 }
27
_upb_FromBase92(uint8_t ch)28 UPB_INLINE char _upb_FromBase92(uint8_t ch) {
29 extern const int8_t _kUpb_FromBase92[];
30 if (' ' > ch || ch > '~') return -1;
31 return _kUpb_FromBase92[ch - ' '];
32 }
33
_upb_Base92_DecodeVarint(const char * ptr,const char * end,char first_ch,uint8_t min,uint8_t max,uint32_t * out_val)34 UPB_INLINE const char* _upb_Base92_DecodeVarint(const char* ptr,
35 const char* end, char first_ch,
36 uint8_t min, uint8_t max,
37 uint32_t* out_val) {
38 uint32_t val = 0;
39 uint32_t shift = 0;
40 const int bits_per_char =
41 upb_Log2Ceiling(_upb_FromBase92(max) - _upb_FromBase92(min));
42 char ch = first_ch;
43 while (1) {
44 uint32_t bits = _upb_FromBase92(ch) - _upb_FromBase92(min);
45 val |= bits << shift;
46 if (ptr == end || *ptr < min || max < *ptr) {
47 *out_val = val;
48 UPB_ASSUME(ptr != NULL);
49 return ptr;
50 }
51 ch = *ptr++;
52 shift += bits_per_char;
53 if (shift >= 32) return NULL;
54 }
55 }
56
57 #ifdef __cplusplus
58 } /* extern "C" */
59 #endif
60
61 #include "upb/port/undef.inc"
62
63 #endif // UPB_MINI_DESCRIPTOR_INTERNAL_BASE92_H_
64