CnC_Remastered_Collection/REDALERT/COORDA.ASM

127 lines
6.8 KiB
NASM

;
; Copyright 2020 Electronic Arts Inc.
;
; TiberianDawn.DLL and RedAlert.dll and corresponding source code 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 3 of the License, or (at your option) any later version.
; TiberianDawn.DLL and RedAlert.dll and corresponding source code is distributed
; in the hope that it will be useful, but with permitted additional restrictions
; under Section 7 of the GPL. See the GNU General Public License in LICENSE.TXT
; distributed with this program. You should have received a copy of the
; GNU General Public License along with permitted additional restrictions
; with this program. If not, see [https://github.com/electronicarts/CnC_Remastered_Collection]>.
;***************************************************************************
;** 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 I N C **
;***************************************************************************
;* *
;* Project Name : Command & Conquer *
;* *
;* File Name : COORDA.ASM *
;* *
;* Programmer : Barry W. Green *
;* *
;* Start Date : February 17, 1995 *
;* *
;* Last Update : February 17, 1995 [BWG] *
;* *
;*-------------------------------------------------------------------------*
;* Functions: *
;* Cardinal_To_Fixed -- Converts cardinal numbers into a fixed point number. *
;* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - *
IDEAL
P386
MODEL USE32 FLAT
global C Cardinal_To_Fixed :NEAR
global C Fixed_To_Cardinal :NEAR
CODESEG
;***********************************************************************************************
;* Cardinal_To_Fixed -- Converts cardinal numbers into a fixed point number. *
;* *
;* This utility function will convert cardinal numbers into a fixed point fraction. The *
;* use of fixed point numbers occurs throughout the product -- since it is a convenient *
;* tool. The fixed point number is based on the formula: *
;* *
;* result = cardinal / base *
;* *
;* The accuracy of the fixed point number is limited to 1/65536 as the lowest and up to *
;* 65536 as the largest. *
;* *
;* INPUT: base -- The key number to base the fraction about. *
;* *
;* cardinal -- The other number (hey -- what do you call it?) *
;* *
;* OUTPUT: Returns with the fixed point number of the "cardinal" parameter as it relates *
;* to the "base" parameter. *
;* *
;* WARNINGS: none *
;* *
;* HISTORY: *
;* 02/17/1995 BWG : Created. *
;*=============================================================================================*/
;unsigned int Cardinal_To_Fixed(unsigned base, unsigned cardinal);
PROC Cardinal_To_Fixed C near
USES ebx, edx
ARG base:DWORD
ARG cardinal:DWORD
mov eax,0FFFFFFFFh ; establish default return value
mov ebx,[base]
or ebx,ebx
jz near ??retneg1 ; if base==0, return 4294967295
mov eax,[cardinal] ; otherwise, return (cardinal*65536)/base
shl eax,16
xor edx,edx
div ebx
??retneg1:
ret
ENDP Cardinal_To_Fixed
;***********************************************************************************************
;* Fixed_To_Cardinal -- Converts a fixed point number into a cardinal number. *
;* *
;* Use this routine to convert a fixed point number into a cardinal number. *
;* *
;* INPUT: base -- The base number that the original fixed point number was created from. *
;* *
;* fixed -- The fixed point number to convert. *
;* *
;* OUTPUT: Returns with the reconverted number. *
;* *
;* WARNINGS: none *
;* *
;* HISTORY: *
;* 02/17/1995 BWG : Created. *
;*=============================================================================================*/
;unsigned int Fixed_To_Cardinal(unsigned base, unsigned fixed);
PROC Fixed_To_Cardinal C near
USES edx
ARG base:DWORD
ARG fixed:DWORD
mov eax,[base]
mul [fixed]
add eax,08000h ; eax = (base * fixed) + 0x8000
shr eax,16 ; return eax/65536
ret
ENDP Fixed_To_Cardinal
END