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// =============================================================================
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// --- kvi_memmove.cpp ---
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// This file is part of the KVIrc IRC client distribution
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// Copyright (C) 1999-2000 Szymon Stefanek (stefanek@tin.it)
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// This program is FREE software. You can redistribute it and/or
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// modify it under the terms of the GNU General Public License
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// as published by the Free Software Foundation; either version 2
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// of the License, or (at your opinion) any later version.
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// This program is distributed in the HOPE that it will be USEFUL,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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// See the GNU General Public License for more details.
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// You should have received a copy of the GNU General Public License
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// along with this program. If not, write to the Free Software Foundation,
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// Inc, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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// =============================================================================
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#include "kvi_debug.h"
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#include "kvi_settings.h"
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#define _KVI_MEMMOVE_CPP_
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#ifdef COMPILE_i386_ASM_CODE
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void *kvi_memmove(void *dst_ptr, const void *src_ptr, int len)
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__range_valid(dst_ptr);
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__range_valid(src_ptr);
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__range_valid(len >= 0);
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// Save pointer registers
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asm(" pushl %esi"); // Save %esi
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asm(" pushl %edi"); // Save %edi
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asm(" movl 16(%ebp),%ecx"); // %ecx = len
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asm(" movl 12(%ebp),%esi"); // %esi = src
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asm(" movl 8(%ebp),%edi"); // %edi = dst
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// Compare src and dest
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asm(" cmpl %esi,%edi"); // %edi - %esi
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asm(" jbe move_from_bottom_to_top"); // If( %edi < %esi ) jump to move_from_bottom_to_top
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asm(" addl %ecx,%esi"); // %esi += %ecx (src_ptr += len);
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asm(" addl %ecx,%edi"); // %edi += %ecx (dst_ptr += len);
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asm(" decl %esi"); // %esi--; (src_ptr--);
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asm(" decl %edi"); // %edi--; (dst_ptr--);
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asm(" std"); // Set direction flag (decrement esi and edi in movsb)
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// Optimization : check for non-odd len (1, 3, 5, 7...)
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asm(" shr $1,%ecx"); // %ecx >> 1, shifted bit -> CF
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asm(" jnc move_two_bytes_top_to_bottom_directly"); // If !carry (CF == 0) skip this move
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// Move the first byte (non-odd)
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asm(" movsb %ds:(%esi),%es:(%edi)"); // *dst-- = *src-- if DF else *dst++ = *src++
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asm("move_two_bytes_top_to_bottom_directly:");
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asm(" decl %esi"); // %esi--; (src_ptr--);
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asm(" decl %edi"); // %edi--; (dst_ptr--);
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asm("move_two_bytes_top_to_bottom:");
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asm(" shr $1,%ecx"); // %ecx >> 1, shifted bit -> CF
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asm(" jnc move_the_rest_top_to_bottom_directly"); // If !carry (CF == 0) skip this move
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// Move the next two bytes
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asm(" movsw %ds:(%esi),%es:(%edi)"); // *((word *)dst)-- = *((word)src)-- if DF else *((word *)dst)++ = *((word)src)++
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asm("move_the_rest_top_to_bottom_directly:");
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asm(" subl $2,%esi"); // %esi -= 2; (src -= 2);
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asm(" subl $2,%edi"); // %edi -= 2; (dst -= 2);
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asm(" jmp move_the_rest"); // Call last repnz movsl
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asm("move_from_bottom_to_top:");
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asm(" cld"); // Clear direction flag (increment esi and edi in movsb)
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// Optimization : check for non-odd len (1, 3, 5, 7...)
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asm(" shr $1,%ecx"); // %ecx >> 1, shifted bit -> CF
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asm(" jnc move_two_bytes"); // If !carry (CF == 0) skip this move
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// Move the first byte (non-odd)
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asm(" movsb %ds:(%esi),%es:(%edi)"); // *dst-- = *src-- if DF else *dst++ = *src++
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// Optimization : pass 2, check for %2 and %3
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asm("move_two_bytes:");
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asm(" shr $1,%ecx"); // %ecx >> 1, shifted bit -> CF
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asm(" jnc move_the_rest"); // If !carry (CF == 0) skip this move
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// Move the next two bytes
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asm(" movsw %ds:(%esi),%es:(%edi)"); // *((word *)dst)-- = *((word)src)-- if DF else *((word *)dst)++ = *((word)src)++
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// Main move remaining part
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asm("move_the_rest:");
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asm(" repnz; movsl %ds:(%esi),%es:(%edi)"); // Loop moving 4 bytes at once (increment or decrement as above)
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// Restore pointer registers
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asm(" popl %edi"); // Restore %edi
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asm(" popl %esi"); // Restore %esi
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#else // COMPILE_i386_ASM_CODE
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void *kvi_memmove(void *dst_ptr, const void *src_ptr, int len)
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__range_valid(dst_ptr);
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__range_valid(src_ptr);
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__range_valid(len >= 0);
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if( dst_ptr > src_ptr ) {
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dst = (char *) dst_ptr + len - 1;
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src = (char *) src_ptr + len - 1;
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while( len-- ) *dst-- = *src--;
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// It is valid even if dst_ptr == src_ptr
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dst = (char *) dst_ptr;
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src = (char *) src_ptr;
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void kvi_fastmove(void *dst_ptr, const void *src_ptr, int len)
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__range_valid(dst_ptr);
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__range_valid(src_ptr);
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__range_valid(len >= 0);
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register const char *src = (const char *) src_ptr;
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register char *dst = (char *) dst_ptr;
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#endif // COMPILE_i386_ASM_CODE
added
removed
src/kvilib/core/kvi_memmove.cpp
