mirror of
https://github.com/electronicarts/CnC_Remastered_Collection
synced 2024-04-28 17:32:32 +12:00
03416d24e1
Initial commit of original Tiberian Dawn and Red Alert source code converted to build as DLLs, and compatible with the release version of Command & Conquer Remastered.
183 lines
5.3 KiB
C++
183 lines
5.3 KiB
C++
//
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// Copyright 2020 Electronic Arts Inc.
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//
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// TiberianDawn.DLL and RedAlert.dll and corresponding source code is free
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// software: you can redistribute it and/or modify it under the terms of
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// the GNU General Public License as published by the Free Software Foundation,
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// either version 3 of the License, or (at your option) any later version.
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// TiberianDawn.DLL and RedAlert.dll and corresponding source code is distributed
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// in the hope that it will be useful, but with permitted additional restrictions
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// under Section 7 of the GPL. See the GNU General Public License in LICENSE.TXT
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// distributed with this program. You should have received a copy of the
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// GNU General Public License along with permitted additional restrictions
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// with this program. If not, see https://github.com/electronicarts/CnC_Remastered_Collection
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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 : IRANDOM.C *
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* *
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* Programmer : Barry W. Green *
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* *
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* Last Update : 10 Feb, 1995 [BWG] *
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* *
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*-------------------------------------------------------------------------*
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* Functions: *
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* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
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#include <stdlib.h>
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#include <time.h>
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#include "misc.h"
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extern "C" unsigned long RandNumb = 0x12349876;
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/* IRANDOM ----------------------------------------------------------
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IRandom returns a random value between min and max inclusive.
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INPUTS: int min and int max
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RETURNS: int random number
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*/
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int IRandom(int minval, int maxval)
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{
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int num,mask;
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// Keep minval and maxval straight.
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if (minval > maxval) {
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minval ^= maxval;
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maxval ^= minval;
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minval ^= maxval;
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}
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mask = Get_Random_Mask(maxval - minval);
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while( (num = (rand() & mask) + minval) > maxval ) ;
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return(num);
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}
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unsigned char Random(void)
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{
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__asm {
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lea esi, [RandNumb] //; get offset in segment of RandNumb
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xor eax,eax
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mov al,[esi]
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shr al,1 //; shift right 1 bit (bit0 in carry)
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shr al,1
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rcl [BYTE PTR esi+2],1 //; rcl byte 3 of RandNumb
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rcl [BYTE PTR esi+1],1 //; rcl byte 2 of RandNumb
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cmc //; complement carry
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sbb al,[esi] //; sbb byte 1 of RandNumb
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shr al,1 //; sets carry
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rcr [BYTE PTR esi],1 //; rcr byte 1 of RandNumb
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mov al,[esi] //; reload byte 1 of RandNumb
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xor al,[esi+1] //; xor with byte 2 of RandNumb
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}
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}
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int Get_Random_Mask(int maxval)
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{
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__asm {
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bsr ecx,[maxval] // ; put bit position of highest bit in ecx
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mov eax, 1 // ; set one bit on in eax
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jz invalid // ; if BSR shows maxval==0, return eax=1
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inc ecx // ; get one bit higher than count showed
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shl eax,cl // ; move our EAX bit into position
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dec eax // ; dec it to create the mask.
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invalid:
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}
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}
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#if (0)
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RandNumb DD 12349876H
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;
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; UBYTE Random(VOID);
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; int Get_Random_Mask(int maxval);
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;
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; ----------------------------------------------------------------
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;-----------------------------------------------------------------
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; RANDOM
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;
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; UBYTE Random(VOID);
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;
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;*
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PROC Random C near
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USES esi
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lea esi, [RandNumb] ; get offset in segment of RandNumb
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xor eax,eax
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mov al,[esi]
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shr al,1 ; shift right 1 bit (bit0 in carry)
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shr al,1
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rcl [BYTE PTR esi+2],1 ; rcl byte 3 of RandNumb
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rcl [BYTE PTR esi+1],1 ; rcl byte 2 of RandNumb
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cmc ; complement carry
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sbb al,[esi] ; sbb byte 1 of RandNumb
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shr al,1 ; sets carry
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rcr [BYTE PTR esi],1 ; rcr byte 1 of RandNumb
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mov al,[esi] ; reload byte 1 of RandNumb
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xor al,[esi+1] ; xor with byte 2 of RandNumb
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ret
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ENDP Random
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;-----------------------------------------------------------------
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; GET_RANDOM_MASK - returns an AND value that is large enough that it
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; encloses the 'maxval' parameter.
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;
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; int Get_Random_Mask(int maxval);
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;
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;*
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PROC Get_Random_Mask C near
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USES ecx
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ARG maxval:DWORD
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; This function takes as a parameter a maximum value, for example, 61. It
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; then tries to create an AND mask that is big enough to enclose that number.
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; For our example case, that AND mask would be 0x3F. It does this by scanning
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; for the highest bit in the number, then making an all-1's mask from that
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; bit position down to bit 0.
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bsr ecx,[maxval] ; put bit position of highest bit in ecx
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mov eax,1 ; set one bit on in eax
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jz ??invalid ; if BSR shows maxval==0, return eax=1
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inc ecx ; get one bit higher than count showed
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shl eax,cl ; move our EAX bit into position
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dec eax ; dec it to create the mask.
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??invalid:
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ret
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ENDP Get_Random_Mask
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;----------------------------------------------------------------------------
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END
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#endif |