106 lines
4.8 KiB
NASM
106 lines
4.8 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 S T U D I O S **
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;***************************************************************************
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;* *
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;* Project Name : Clear the Full Mcga Screen *
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;* *
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;* File Name : GETPIXEL.ASM *
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;* *
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;* Programmer : Phil Gorrow *
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;* *
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;* Start Date : June 7, 1994 *
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;* *
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;* Last Update : June 7, 1994 [PWG] *
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;* *
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;*-------------------------------------------------------------------------*
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;* Functions: *
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;* VVPC::Clear -- Clears a virtual viewport instance *
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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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INCLUDE "mcgaprim.inc"
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INCLUDE ".\gbuffer.inc"
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CODESEG
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;***************************************************************************
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;* VVPC::GET_PIXEL -- Gets a pixel from the current view port *
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;* *
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;* INPUT: WORD the x pixel on the screen. *
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;* WORD the y pixel on the screen. *
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;* *
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;* OUTPUT: UBYTE the pixel at the specified location *
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;* *
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;* WARNING: If pixel is to be placed outside of the viewport then *
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;* this routine will abort. *
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;* *
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;* HISTORY: *
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;* 06/07/1994 PWG : Created. *
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;*=========================================================================*
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PROC MCGA_Get_Pixel C near
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USES ebx,ecx,edx,edi
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ARG this:DWORD ; this is a member function
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ARG x_pixel:DWORD ; x position of pixel to set
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ARG y_pixel:DWORD ; y position of pixel to set
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;*===================================================================
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; Get the viewport information and put bytes per row in ecx
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;*===================================================================
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mov ebx,[this] ; get a pointer to viewport
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xor eax,eax
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mov edi,[(GraphicViewPort ebx).GVPOffset] ; get the correct offset
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mov ecx,[(GraphicViewPort ebx).GVPHeight] ; edx = height of viewport
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mov edx,[(GraphicViewPort ebx).GVPWidth] ; ecx = width of viewport
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;*===================================================================
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; Verify that the X pixel offset if legal
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;*===================================================================
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mov eax,[x_pixel] ; find the x position
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cmp eax,edx ; is it out of bounds
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jae short ??exit ; if so then get out
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add edi,eax ; otherwise add in offset
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;*===================================================================
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; Verify that the Y pixel offset if legal
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;*===================================================================
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mov eax,[y_pixel] ; get the y position
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cmp eax,ecx ; is it out of bounds
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jae ??exit ; if so then get out
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add edx,[(GraphicViewPort ebx).GVPXAdd] ; otherwise find bytes per row
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mul edx ; offset = bytes per row * y
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add edi,eax ; add it into the offset
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;*===================================================================
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; Write the pixel to the screen
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;*===================================================================
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xor eax,eax ; clear the word
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mov al,[edi] ; read in the pixel
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??exit:
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ret
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ENDP MCGA_Get_Pixel
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END
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