bdiff: don't check border condition in loop
This is pretty much a copy of d500ddae7494, just to a different loop.
The condition `p == plast` (`plast == a + len - 1`) was only true on
the final iteration of the loop. So it was wasteful to check for it
on every iteration. We decrease the iteration count by 1 and add an
explicit check for `p == plast` after the loop.
Again, we see modest wins.
From the mozilla-unified repository:
$ perfbdiff -m 3041e4d59df2
! wall 0.035502 comb 0.040000 user 0.040000 sys 0.000000 (best of 100)
! wall 0.030480 comb 0.030000 user 0.030000 sys 0.000000 (best of 100)
$ perfbdiff 0e9928989e9c --alldata --count 100
! wall 4.097394 comb 4.100000 user 4.100000 sys 0.000000 (best of 3)
! wall 3.597798 comb 3.600000 user 3.600000 sys 0.000000 (best of 3)
The 2nd example throws a total of ~3.3GB of data at bdiff. This
change increases the throughput from ~811 MB/s to ~924 MB/s.
/**
* Copyright (c) 2016-present, Yann Collet, Facebook, Inc.
* All rights reserved.
*
* This source code is licensed under the BSD-style license found in the
* LICENSE file in the root directory of this source tree. An additional grant
* of patent rights can be found in the PATENTS file in the same directory.
*/
/*-*************************************
* Dependencies
***************************************/
#include <stdlib.h> /* malloc */
#include "error_private.h"
#define ZSTD_STATIC_LINKING_ONLY
#include "zstd.h" /* declaration of ZSTD_isError, ZSTD_getErrorName, ZSTD_getErrorCode, ZSTD_getErrorString, ZSTD_versionNumber */
#include "zbuff.h" /* declaration of ZBUFF_isError, ZBUFF_getErrorName */
/*-****************************************
* Version
******************************************/
unsigned ZSTD_versionNumber (void) { return ZSTD_VERSION_NUMBER; }
/*-****************************************
* ZSTD Error Management
******************************************/
/*! ZSTD_isError() :
* tells if a return value is an error code */
unsigned ZSTD_isError(size_t code) { return ERR_isError(code); }
/*! ZSTD_getErrorName() :
* provides error code string from function result (useful for debugging) */
const char* ZSTD_getErrorName(size_t code) { return ERR_getErrorName(code); }
/*! ZSTD_getError() :
* convert a `size_t` function result into a proper ZSTD_errorCode enum */
ZSTD_ErrorCode ZSTD_getErrorCode(size_t code) { return ERR_getErrorCode(code); }
/*! ZSTD_getErrorString() :
* provides error code string from enum */
const char* ZSTD_getErrorString(ZSTD_ErrorCode code) { return ERR_getErrorName(code); }
/* **************************************************************
* ZBUFF Error Management
****************************************************************/
unsigned ZBUFF_isError(size_t errorCode) { return ERR_isError(errorCode); }
const char* ZBUFF_getErrorName(size_t errorCode) { return ERR_getErrorName(errorCode); }
/*=**************************************************************
* Custom allocator
****************************************************************/
/* default uses stdlib */
void* ZSTD_defaultAllocFunction(void* opaque, size_t size)
{
void* address = malloc(size);
(void)opaque;
return address;
}
void ZSTD_defaultFreeFunction(void* opaque, void* address)
{
(void)opaque;
free(address);
}
void* ZSTD_malloc(size_t size, ZSTD_customMem customMem)
{
return customMem.customAlloc(customMem.opaque, size);
}
void ZSTD_free(void* ptr, ZSTD_customMem customMem)
{
if (ptr!=NULL)
customMem.customFree(customMem.opaque, ptr);
}