ceph/src/isa-l/igzip/bitbuf2.h

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   2   Copyright(c) 2011-2016 Intel Corporation All rights reserved.
   3
   4   Redistribution and use in source and binary forms, with or without
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  28 **********************************************************************/
  29 #ifndef BITBUF2_H
  30 #define BITBUF2_H
  31
  32 #include "igzip_lib.h"
  33
  34 #if defined (__unix__) || (__APPLE__)
  35 #define _mm_stream_si64x(dst, src) *((uint64_t*)dst) = src
  36 #else
  37 #include <intrin.h>
  38 #endif
  39
  40 #ifdef _WIN64
  41 #pragma warning(disable: 4996)
  42 #endif
  43
  44 #ifdef _MSC_VER
  45 #define inline __inline
  46 #endif
  47
  48
  49 /* MAX_BITBUF_BIT WRITE is the maximum number of bits than can be safely written
  50  * by consecutive calls of write_bits. Note this assumes the bitbuf is in a
  51  * state that is possible at the exit of write_bits */
  52 #ifdef USE_BITBUF8 /*Write bits safe */
  53 # define MAX_BITBUF_BIT_WRITE 63
  54 #elif defined(USE_BITBUFB) /* Write bits always */
  55 # define MAX_BITBUF_BIT_WRITE 56
  56 #else /* USE_BITBUF_ELSE */
  57 # define MAX_BITBUF_BIT_WRITE 56
  58 #endif
  59
  60
  61 static
  62  inline void construct(struct BitBuf2 *me)
  63 {
  64         me->m_bits = 0;
  65         me->m_bit_count = 0;
  66         me->m_out_buf = me->m_out_start = me->m_out_end = NULL;
  67 }
  68
  69 static inline void init(struct BitBuf2 *me)
  70 {
  71         me->m_bits = 0;
  72         me->m_bit_count = 0;
  73 }
  74
  75 static inline void set_buf(struct BitBuf2 *me, unsigned char *buf, unsigned int len)
  76 {
  77         unsigned int slop = 8;
  78         me->m_out_buf = me->m_out_start = buf;
  79         me->m_out_end = buf + len - slop;
  80 }
  81
  82 static inline int is_full(struct BitBuf2 *me)
  83 {
  84         return (me->m_out_buf > me->m_out_end);
  85 }
  86
  87 static inline uint8_t * buffer_ptr(struct BitBuf2 *me)
  88 {
  89         return me->m_out_buf;
  90 }
  91
  92 static inline uint32_t buffer_used(struct BitBuf2 *me)
  93 {
  94         return (uint32_t)(me->m_out_buf - me->m_out_start);
  95 }
  96
  97 static inline void check_space(struct BitBuf2 *me, uint32_t num_bits)
  98 {
  99         /* Checks if bitbuf has num_bits extra space and flushes the bytes in
 100          * the bitbuf if it doesn't. */
 101         uint32_t bytes;
 102         if (63 - me->m_bit_count < num_bits) {
 103                 _mm_stream_si64x((int64_t *) me->m_out_buf, me->m_bits);
 104                 bytes = me->m_bit_count / 8;
 105                 me->m_out_buf += bytes;
 106                 bytes *= 8;
 107                 me->m_bit_count -= bytes;
 108                 me->m_bits >>= bytes;
 109         }
 110 }
 111
 112 static inline void write_bits_unsafe(struct BitBuf2 *me, uint64_t code, uint32_t count)
 113 {
 114         me->m_bits |= code << me->m_bit_count;
 115         me->m_bit_count += count;
 116 }
 117
 118 static inline void write_bits(struct BitBuf2 *me, uint64_t code, uint32_t count)
 119 {
 120 #ifdef USE_BITBUF8 /*Write bits safe */
 121         me->m_bits |= code << me->m_bit_count;
 122         me->m_bit_count += count;
 123         if (me->m_bit_count >= 64) {
 124                 _mm_stream_si64x((int64_t *) me->m_out_buf, me->m_bits);
 125                 me->m_out_buf += 8;
 126                 me->m_bit_count -= 64;
 127                 me->m_bits = code >> (count - me->m_bit_count);
 128         }
 129 #elif defined(USE_BITBUFB) /* Write bits always */
 130         /* Assumes there is space to fit code into m_bits. */
 131         uint32_t bits;
 132         me->m_bits |= code << me->m_bit_count;
 133         me->m_bit_count += count;
 134         if (me->m_bit_count >= 8) {
 135                 _mm_stream_si64x((int64_t *) me->m_out_buf, me->m_bits);
 136                 bits = me->m_bit_count & ~7;
 137                 me->m_bit_count -= bits;
 138                 me->m_out_buf += bits/8;
 139                 me->m_bits >>= bits;
 140         }
 141 #else /* USE_BITBUF_ELSE */
 142         check_space(me, count);
 143         write_bits_unsafe(me, code, count);
 144 #endif
 145
 146 }
 147
 148 /* Can write up to 8 bytes to output buffer */
 149 static inline void flush(struct BitBuf2 *me)
 150 {
 151         uint32_t bytes;
 152         if (me->m_bit_count) {
 153                 _mm_stream_si64x((int64_t *) me->m_out_buf, me->m_bits);
 154                 bytes = (me->m_bit_count + 7) / 8;
 155                 me->m_out_buf += bytes;
 156         }
 157         me->m_bits = 0;
 158         me->m_bit_count = 0;
 159 }
 160
 161 #endif //BITBUF2_H