184 lines
6.5 KiB
NASM
184 lines
6.5 KiB
NASM
;
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; Command & Conquer Red Alert(tm)
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; Copyright 2025 Electronic Arts Inc.
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;
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; This program is free software: you can redistribute it and/or modify
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; it under the terms of the GNU General Public License as published by
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; the Free Software Foundation, either version 3 of the License, or
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; (at your option) any later version.
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;
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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. See the
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; GNU General Public License for more details.
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;
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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, see <http://www.gnu.org/licenses/>.
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;
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;***************************************************************************
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;** C O N F I D E N T I A L --- W E S T W O O D A S S O C I A T E S **
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;***************************************************************************
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;* *
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;* Project Name : LIBRARY *
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;* *
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;* File Name : MEM_COPY.ASM *
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;* *
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;* Programmer : Scott Bowen *
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;* *
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;* Last Update : September 8, 1994 [IML] *
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;* Ported to watcom c32 : 01/03/96 [JRJ] *
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;*-------------------------------------------------------------------------*
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;* Functions: *
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;* Mem_Copy -- Copies from one pointer to another. *
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;* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - *
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IDEAL
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P386
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MODEL USE32 FLAT
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LOCALS ??
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;******************************************************************************
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; Much testing was done to determine that only when there are 14 or more bytes
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; being copied does it speed the time it takes to do copies in this algorithm.
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; For this reason and because 1 and 2 byte copies crash, is the special case
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; used. SKB 4/21/94. Tested on 486 66mhz.
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OPTIMAL_BYTE_COPY equ 14
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;******************************************************************************
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; External declares so these functions can be called
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;
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GLOBAL C Mem_Copy : NEAR
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GLOBAL C Largest_Mem_Block : near
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CODESEG
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;***************************************************************************
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;* MEM_COPY -- Copies from one pointer to another. *
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;* This routine copies bytes from source to dest. It takes care of *
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;* overlapped memory, and unsigned long copies. *
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;* *
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;* *
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;* *
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;* *
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;* INPUT: *
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;* *
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;* OUTPUT: *
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;* *
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;* WARNINGS: *
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;* *
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;* HISTORY: *
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;* 04/18/1994 SKB : Created. *
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;*=========================================================================*
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; void Mem_Copy(void *source, void *dest, unsigned long bytes_to_copy);
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PROC Mem_Copy C near
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USES ecx , esi , edi , ebx
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ARG source:DWORD
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ARG dest:DWORD
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ARG bytes:DWORD
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;********************************* Setup ******************************************
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cld
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mov esi,[source]
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mov edi,[dest]
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mov ecx,[bytes] ; get number of bytes to copy.
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; check pointers for singularities
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cmp esi,edi ; Compare source with dest.
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je ??done ; No sence in copying the same pointer.
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or esi,0
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jz ??done
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or edi,0
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jz ??done
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cmp ecx,OPTIMAL_BYTE_COPY ; see notes above about equate.
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jge ??normal ; If >= MAX(2,OPTIMAL_BYTE_COPY), do normal dword copy.
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;******************************** Special case <= 2 *******************************
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;
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; This section must be called for bytes <= 2 since the other case will crash. It
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; optionally uses OPTIMAL_BYTE_COPY for the cut off point. This is because after
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; extensive testing, it was proved that only at that point (14 or more bytes) does
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; it become quicker to use the dword copy method.
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cmp esi,edi ; Compare source with dest.
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jge ??do_move ; if source greater do forward copy.
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lea esi,[esi+ecx-1]
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std ; Opps, wrong, force the pointers to decrement.
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lea edi,[edi+ecx-1]
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??do_move:
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rep movsb ; move the one or two bytes.
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cld
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??done:
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ret
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;************************** back or forth, that is the question *******************
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??normal:
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mov ebx,ecx
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cmp esi,edi ; Compare source with dest.
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jge ??forward ; if source greater do forward copy.
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;********************************* Backward ***************************************
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??backward:
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lea ecx,[edi+ebx]
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std
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lea edi,[edi+ebx-1]
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and ecx,3 ; Get non aligned bytes.
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lea esi,[esi+ebx-1]
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sub ebx,ecx ; remove that from the total size to be copied later.
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rep movsb ; do the copy.
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sub esi,3
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mov ecx,ebx ; Get number of bytes left.
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sub edi,3
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shr ecx,2 ; Do 4 bytes at a time.
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rep movsd ; do the dword copy.
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mov ecx,ebx
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add esi,3
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add edi,3
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and ecx,03h
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rep movsb ; finnish the remaining bytes.
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cld
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ret
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;********************************* Forward ***************************************
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??forward:
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cld
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mov ecx,edi ; get destination pointer.
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neg ecx
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and ecx,3 ; Get non aligned bytes.
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sub ebx,ecx ; remove that from the total size to be copied later.
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rep movsb ; do the copy.
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mov ecx,ebx ; Get number of bytes left.
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shr ecx,2 ; Do 4 bytes at a time.
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rep movsd ; do the dword copy.
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mov ecx, ebx
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and ecx,03h
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rep movsb ; finnish the remaining bytes.
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ret
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ENDP Mem_Copy
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PROC Largest_Mem_Block C near
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uses esi , edi , ebx , ecx , edx
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local mem_struct : dword : 16
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mov eax , 0500h
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lea edi , [ mem_struct ]
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int 31h
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mov eax , [ mem_struct ]
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ret
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ENDP Largest_Mem_Block
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END
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