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//=============================================================================
//
// File : kvi_memmove.cpp
// Creation date : Sun Jun 18 2000 18:27:50 CEST by Szymon Stefanek
//
// This file is part of the KVirc irc client distribution
// Copyright (C) 1999-2006 Szymon Stefanek (pragma at kvirc dot net)
//
// This program is FREE software. You can redistribute it and/or
// modify it under the terms of the GNU General Public License
// as published by the Free Software Foundation; either version 2
// of the License, or (at your opinion) any later version.
//
// This program is distributed in the HOPE that it will be USEFUL,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
// See the GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program. If not, write to the Free Software Foundation,
// Inc. ,51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
//
//=============================================================================
#define __KVILIB__
#define _KVI_DEBUG_CHECK_RANGE_
#include "kvi_debug.h"
#define _KVI_MEMMOVE_CPP_
#include "kvi_memmove.h"
// FIXME: #warning "With system memmove could be guessed by configure"
#ifndef COMPILE_WITH_SYSTEM_MEMMOVE
#ifdef COMPILE_ix86_ASM
void *kvi_memmove(void * dst_ptr,const void *src_ptr,int len)
{
__range_valid(dst_ptr);
__range_valid(src_ptr);
__range_valid(len >= 0);
// Save pointer registers
asm(" pushl %esi"); // save %esi
asm(" pushl %edi"); // save %edi
// Load arguments
asm(" movl 16(%ebp),%ecx"); // %ecx = len
asm(" movl 12(%ebp),%esi"); // %esi = src
asm(" movl 8(%ebp),%edi"); // %edi = dst
// Compare src and dest
asm(" cmpl %esi,%edi"); // %edi - %esi
asm(" jbe move_from_bottom_to_top"); // if(%edi < %esi) jump to move_from_bottom_to_top
// dst_ptr > src_ptr
asm(" addl %ecx,%esi"); // %esi += %ecx (src_ptr += len);
asm(" addl %ecx,%edi"); // %edi += %ecx (dst_ptr += len);
asm(" decl %esi"); // %esi--; (src_ptr--);
asm(" decl %edi"); // %edi--; (dst_ptr--);
asm(" std"); // set direction flag (decrement esi and edi in movsb)
// Optimization : check for non-odd len (1,3,5,7...)
asm(" shr $1,%ecx"); // %ecx >> 1 , shifted bit -> CF
asm(" jnc move_two_bytes_top_to_bottom_directly"); // if !carry (CF == 0) skip this move
// Move the first byte (non-odd)
asm(" movsb %ds:(%esi),%es:(%edi)"); // *dst-- = *src-- if DF else *dst++ = *src++
asm("move_two_bytes_top_to_bottom_directly:");
asm(" decl %esi"); // %esi--; (src_ptr--);
asm(" decl %edi"); // %edi--; (dst_ptr--);
asm("move_two_bytes_top_to_bottom:");
asm(" shr $1,%ecx"); // %ecx >> 1 , shifted bit -> CF
asm(" jnc move_the_rest_top_to_bottom_directly"); // if !carry (CF == 0) skip this move
// Move the next two bytes
asm(" movsw %ds:(%esi),%es:(%edi)"); // *((word *)dst)-- = *((word)src)-- if DF else *((word *)dst)++ = *((word)src)++
asm("move_the_rest_top_to_bottom_directly:");
asm(" subl $2,%esi"); // %esi-=2; (src-=2);
asm(" subl $2,%edi"); // %edi-=2; (dst-=2);
asm(" jmp move_the_rest"); // call last repnz movsl
// dst_ptr <= src_ptr
asm("move_from_bottom_to_top:");
asm(" cld"); // clear direction flag (increment esi and edi in movsb)
// Optimization : check for non-odd len (1,3,5,7...)
asm(" shr $1,%ecx"); // %ecx >> 1 , shifted bit -> CF
asm(" jnc move_two_bytes"); // if !carry (CF == 0) skip this move
// Move the first byte (non-odd)
asm(" movsb %ds:(%esi),%es:(%edi)"); // *dst-- = *src-- if DF else *dst++ = *src++
// Optimization : pass 2 , check for %2 and %3
asm("move_two_bytes:");
asm(" shr $1,%ecx"); // %ecx >> 1 , shifted bit -> CF
asm(" jnc move_the_rest"); // if !carry (CF == 0) skip this move
// Move the next two bytes
asm(" movsw %ds:(%esi),%es:(%edi)"); // *((word *)dst)-- = *((word)src)-- if DF else *((word *)dst)++ = *((word)src)++
// Main move remaining part
asm("move_the_rest:");
asm(" repnz; movsl %ds:(%esi),%es:(%edi)"); // loop moving 4 bytes at once (increment or decrement as above)
// Restore pointer registers
asm(" popl %edi"); // restore %edi
asm(" popl %esi"); // restore %esi
return dst_ptr; //asm(" movl 8(%ebp),%eax"); <-- gcc will put that (AFTER THE OPTIMISATION PASS!)
}
void *kvi_memmoveodd(void * dst_ptr,const void *src_ptr,int len)
{
__range_valid(dst_ptr);
__range_valid(src_ptr);
__range_valid(len >= 0);
// Save pointer registers
asm(" pushl %esi"); // save %esi
asm(" pushl %edi"); // save %edi
// Load arguments
asm(" movl 16(%ebp),%ecx"); // %ecx = len
asm(" movl 12(%ebp),%esi"); // %esi = src
asm(" movl 8(%ebp),%edi"); // %edi = dst
// Compare src and dest
asm(" cmpl %esi,%edi"); // %edi - %esi
asm(" jbe xmove_from_bottom_to_top"); // if(%edi < %esi) jump to move_from_bottom_to_top
// dst_ptr > src_ptr
asm(" addl %ecx,%esi"); // %esi += %ecx (src_ptr += len);
asm(" addl %ecx,%edi"); // %edi += %ecx (dst_ptr += len);
asm(" std"); // set direction flag (decrement esi and edi in movsb)
// start moving
asm(" shr $2,%ecx"); // %ecx >> 2 , last shifted bit -> CF
asm(" jnc xmove_the_rest_top_to_bottom_directly"); // if !carry (CF == 0) skip this move
// Move the next two bytes
asm(" subl $2,%esi"); // %esi-=2; (src_ptr-=2);
asm(" subl $2,%edi"); // %edi-=2; (dst_ptr-=2);
asm(" movsw %ds:(%esi),%es:(%edi)"); // *((word *)dst)-- = *((word)src)-- if DF else *((word *)dst)++ = *((word)src)++
asm(" subl $2,%esi"); // %esi-=2; (src_ptr-=2);
asm(" subl $2,%edi"); // %edi-=2; (dst_ptr-=2);
asm(" jmp xmove_the_rest");
asm("xmove_the_rest_top_to_bottom_directly:");
asm(" subl $4,%esi"); // %esi-=4; (src-=4);
asm(" subl $4,%edi"); // %edi-=4; (dst-=4);
asm(" jmp xmove_the_rest"); // call last repnz movsl
// dst_ptr <= src_ptr
asm("xmove_from_bottom_to_top:");
asm(" cld"); // clear direction flag (increment esi and edi in movsb)
// move it
asm(" shr $2,%ecx"); // %ecx >> 2 , last shifted bit -> CF
asm(" jnc xmove_the_rest"); // if !carry (CF == 0) skip this move
// Move the next two bytes
asm(" movsw %ds:(%esi),%es:(%edi)"); // *((word *)dst)-- = *((word)src)-- if DF else *((word *)dst)++ = *((word)src)++
// Main move remaining part
asm("xmove_the_rest:");
asm(" repnz; movsl %ds:(%esi),%es:(%edi)"); // loop moving 4 bytes at once (increment or decrement as above)
// Restore pointer registers
asm(" popl %edi"); // restore %edi
asm(" popl %esi"); // restore %esi
return dst_ptr; //asm(" movl 8(%ebp),%eax"); <-- gcc will put that (AFTER THE OPTIMISATION PASS!)
}
#else // ndef COMPILE_ix86_ASM
// The next 4 functions could be optimized with the & and shift technique
// used in the assembly implementations but the compilers usually
// will not translate the carry bit trick producing code
// that works slower on short block of memory (really near the average case)
// The trick would be:
//
// if(len & 1) // the length is even
// *dst-- = *src--; // move one byte
// len >> 1; // drop the last bit (thus divide by 2)
// if(len & 1) // the length is still even
// *((short *)dst)-- = *((short *)src)--; // move two bytes
// len >> 1; // again drop the last bit (thus divide by 2)
// while(len--)*((int *)dst)-- = *((int *)src)--; // move four bytes at a time
//
//
void *kvi_memmove(void *dst_ptr,const void *src_ptr,int len)
{
__range_valid(dst_ptr);
__range_valid(src_ptr);
__range_valid(len >= 0);
char *dst;
const char *src;
if(dst_ptr > src_ptr){
dst = (char *)dst_ptr + len - 1;
src = (const char *)src_ptr + len - 1;
while(len--)*dst-- = *src--;
} else { //it is valid even if dst_ptr == src_ptr
dst = (char *)dst_ptr;
src = (const char *)src_ptr;
while(len--)*dst++ = *src++;
}
return dst_ptr;
}
void *kvi_memmoveodd(void *dst_ptr,const void *src_ptr,int len)
{
__range_valid(dst_ptr);
__range_valid(src_ptr);
__range_valid(len >= 0);
__range_valid((len & 1) == 0);
short *dst;
const short *src;
if(dst_ptr > src_ptr){
dst = (short *) (((char *)dst_ptr) + len - 2);
src = (const short *) (((const char *)src_ptr) + len - 2);
while(len > 0)
{
*dst-- = *src--;
len -= 2;
}
} else { //it is valid even if dst_ptr == src_ptr
dst = (short *)dst_ptr;
src = (const short *)src_ptr;
while(len > 0)
{
*dst++ = *src++;
len -= 2;
}
}
return dst_ptr;
}
void kvi_fastmove(void *dst_ptr,const void *src_ptr,int len)
{
__range_valid(dst_ptr);
__range_valid(src_ptr);
__range_valid(len >= 0);
const char *src = (const char *)src_ptr;
char *dst = (char *)dst_ptr;
while(len--)*dst++ = *src++;
}
void kvi_fastmoveodd(void *dst_ptr,const void *src_ptr,int len)
{
__range_valid(dst_ptr);
__range_valid(src_ptr);
__range_valid(len >= 0);
__range_valid((len & 1) == 0);
const short *src = (const short *)src_ptr;
short *dst = (short *)dst_ptr;
while(len > 0){
*dst++ = *src++;
len -= 2;
}
}
#endif // !COMPILE_ix86_ASM
void kvi_memset(void *dst_ptr,char c,int len)
{
__range_valid(dst_ptr);
__range_valid(len >= 0);
char *dst = (char *)dst_ptr;
while(len--)*dst++ = c;
}
#endif // !COMPILE_WITH_SYSTEM_MEMMOVE
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