132 lines
5.0 KiB
NASM
132 lines
5.0 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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; $Header: g:/library/wwlib32/file/rcs/pack2pln.asm 1.1 1994/04/22 18:07:46 scott_bowen Exp $
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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 : PACK2PLN.ASM *
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;* *
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;* Programmer : Scott K. Bowen *
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;* *
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;* Start Date : November 20, 1991 *
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;* *
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;* Last Update : April 22, 1994 [SKB] *
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;* *
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;*-------------------------------------------------------------------------*
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;* Functions: *
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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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; External declares so these functions can be called
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;
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GLOBAL Pack_2_Plane:NEAR
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CODESEG
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;***************************************************************************
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;* PACK_2_PLANE -- packed to planar scanline conversion *
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;* *
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;* INPUT: BYTE *buffer (far) -- pointer to planar output buffer *
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;* BYTE *pageptr (far) -- pointer to current row in packed page *
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;* WORD planebit -- current bit used in plane -- use only low byte *
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;* *
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;* OUTPUT: *
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;* Return result in buffer. *
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;* WARNINGS: *
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;* *
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;* HISTORY: *
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;* 11/20/1991 SB : Created. *
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;* 04/22/1994 SKB : Converted to 32 bit library. *
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;*=========================================================================*
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; *
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; This is the original function that is converted to asm
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;
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;PRIVATE VOID Pack_2_Plane(UBYTE * buffer, BYTE * pageptr, BYTE planebit)
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;{
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; WORD currbit=0x80; // current bit to be written to
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; WORD pixel; // current pixel in row used as a counter;
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;
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; buffer--; // will be incremented at the start
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; for (currbit = 0, pixel = 0; pixel < 320; pixel++) {
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; if (!currbit) {
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; currbit = 0x80; // reset bit 7
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; buffer++; // go to next byte in buffer
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; *buffer = 0; // clear byte so we only need to set bits needed
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; }
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; if (planebit & *pageptr++)
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; *buffer |= currbit; // set bit in destination if plane was set is source
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;
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; currbit >>= 1; // shift destination bit one right
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; }
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;}
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PROC Pack_2_Plane C NEAR
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USES ebx,ecx,esi,edi
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ARG buffer:DWORD
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ARG page:DWORD
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ARG planebit:WORD
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mov edi,[buffer]
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mov esi,[page]
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mov ax,[planebit] ; move bit set for current plane (planebit) to ax
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; the low byte will only be used
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mov ecx,320d ; set counter to 320 columns (320x200 picture)
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mov ah,80h ; set bit 7 of current_bit
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dec edi ; this will get incremented at the start
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??top_loop: ; while (columns left)
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cmp ah,80h ; if current_bit is bit 7
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jnz short ??same_dest
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; Then
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inc edi ; buffer++ increment pointer
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mov [BYTE PTR edi],0 ; *buffer = 0
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??same_dest: ; EndIf
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mov bl,al
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and bl,[esi] ; if (planebit & *pageptr)
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jz short ??no_set_bit
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or [BYTE PTR edi],ah ; Then *buffer |= current_bit
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??no_set_bit:
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inc esi ; pageptr++ goto next in source byte
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ror ah,1 ; rotate current_bit right one
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dec ecx ;
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jnz ??top_loop
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ret
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ENDP Pack_2_Plane
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END
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