Refactor varint encoding/decoding.

1 files changed, 0 insertions, 155 deletions

diff --git a/src/upb_varint_decoder.h b/src/upb_varint_decoder.h
deleted file mode 100644
index d7af90a..0000000
--- a/src/upb_varint_decoder.h
+++ /dev/null
@@ -1,155 +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 decoding (we keep them all around to have
- * multiple approaches available for benchmarking).  All of these functions
- * require the buffer to have at least 10 bytes available; if we don't know
- * for sure that there are 10 bytes, then there is only one viable option
- * (branching on every byte).
- */
-
-#ifndef UPB_VARINT_DECODER_H_
-#define UPB_VARINT_DECODER_H_
-
-#include "upb.h"
-#include <stdint.h>
-#include <string.h>
-
-#ifdef __cplusplus
-extern "C" {
-#endif
-
-// 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).
-INLINE upb_decoderet upb_vdecode_max8_wright(upb_decoderet r) {
-  uint64_t b;
-  memcpy(&b, r.p, sizeof(b));
-  uint64_t cbits = b | 0x7f7f7f7f7f7f7f7fULL;
-  uint64_t stop_bit = ~cbits & (cbits+1);
-  b &= (stop_bit - 1);
-  b = ((b & 0x7f007f007f007f00) >> 1) | (b & 0x007f007f007f007f);
-  b = ((b & 0xffff0000ffff0000) >> 2) | (b & 0x0000ffff0000ffff);
-  b = ((b & 0xffffffff00000000) >> 4) | (b & 0x00000000ffffffff);
-  if (stop_bit == 0) {
-    // Error: unterminated varint.
-    upb_decoderet err_r = {(void*)0, 0};
-    return err_r;
-  }
-  upb_decoderet my_r = {r.p + ((__builtin_ctzll(stop_bit) + 1) / 8),
-                        r.val | (b << 14)};
-  return my_r;
-}
-
-// Another implementation of the previous.
-INLINE upb_decoderet upb_vdecode_max8_massimino(upb_decoderet r) {
-  uint64_t b;
-  memcpy(&b, r.p, sizeof(b));
-  uint64_t cbits = b | 0x7f7f7f7f7f7f7f7fULL;
-  uint64_t stop_bit = ~cbits & (cbits + 1);
-  b =  (b & 0x7f7f7f7f7f7f7f7fULL) & (stop_bit - 1);
-  b +=       b & 0x007f007f007f007fULL;
-  b +=  3 * (b & 0x0000ffff0000ffffULL);
-  b += 15 * (b & 0x00000000ffffffffULL);
-  if (stop_bit == 0) {
-    // Error: unterminated varint.
-    upb_decoderet err_r = {(void*)0, 0};
-    return err_r;
-  }
-  upb_decoderet my_r = {r.p + ((__builtin_ctzll(stop_bit) + 1) / 8),
-                        r.val | (b << 7)};
-  return my_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) {        \
-  uint64_t b = 0;                                                        \
-  upb_decoderet r = {p, 0};                                              \
-  memcpy(&b, r.p, 2);                                                    \
-  if ((b & 0x80) == 0) { r.val = (b & 0x7f); r.p = p + 1; return r; }    \
-  r.val = (b & 0x7f) | ((b & 0x7f00) >> 1);                              \
-  r.p = p + 2;                                                           \
-  if ((b & 0x8000) == 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);
-}
-
-#ifdef __cplusplus
-}  /* extern "C" */
-#endif
-
-#endif  /* UPB_VARINT_DECODER_H_ */