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ID_US_A.ASM
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/
ID_US_A.ASM
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; Catacomb 3-D Source Code
; Copyright (C) 1993-2014 Flat Rock Software
;
; This program 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 2 of the License, or
; (at your option) any later version.
;
; This program is distributed in the hope that it will be useful,
; but WITHOUT ANY WARRANTY; without even the implied warranty of
; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
; GNU General Public License for more details.
;
; You should have received a copy of the GNU General Public License along
; with this program; if not, write to the Free Software Foundation, Inc.,
; 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
IDEAL
MODEL MEDIUM,C
; Assembly portion of the User Mgr. This is just John Carmack's table
; driven pseudo-random number generator, and we put it in the User Mgr
; because we couldn't figure out where it should go
;============================================================================
;
; RANDOM ROUTINES
;
;============================================================================
FARDATA
rndindex dw ?
rndtable db 0, 8, 109, 220, 222, 241, 149, 107, 75, 248, 254, 140, 16, 66
db 74, 21, 211, 47, 80, 242, 154, 27, 205, 128, 161, 89, 77, 36
db 95, 110, 85, 48, 212, 140, 211, 249, 22, 79, 200, 50, 28, 188
db 52, 140, 202, 120, 68, 145, 62, 70, 184, 190, 91, 197, 152, 224
db 149, 104, 25, 178, 252, 182, 202, 182, 141, 197, 4, 81, 181, 242
db 145, 42, 39, 227, 156, 198, 225, 193, 219, 93, 122, 175, 249, 0
db 175, 143, 70, 239, 46, 246, 163, 53, 163, 109, 168, 135, 2, 235
db 25, 92, 20, 145, 138, 77, 69, 166, 78, 176, 173, 212, 166, 113
db 94, 161, 41, 50, 239, 49, 111, 164, 70, 60, 2, 37, 171, 75
db 136, 156, 11, 56, 42, 146, 138, 229, 73, 146, 77, 61, 98, 196
db 135, 106, 63, 197, 195, 86, 96, 203, 113, 101, 170, 247, 181, 113
db 80, 250, 108, 7, 255, 237, 129, 226, 79, 107, 112, 166, 103, 241
db 24, 223, 239, 120, 198, 58, 60, 82, 128, 3, 184, 66, 143, 224
db 145, 224, 81, 206, 163, 45, 63, 90, 168, 114, 59, 33, 159, 95
db 28, 139, 123, 98, 125, 196, 15, 70, 194, 253, 54, 14, 109, 226
db 71, 17, 161, 93, 186, 87, 244, 138, 20, 52, 123, 251, 26, 36
db 17, 46, 52, 231, 232, 76, 31, 221, 84, 37, 216, 165, 212, 106
db 197, 242, 98, 43, 39, 175, 254, 145, 190, 84, 118, 222, 187, 136
db 120, 163, 236, 249
CODESEG
LastRnd dw ?
;=================================================
;
; void US_InitRndT (boolean randomize)
; Init table based RND generator
; if randomize is false, the counter is set to 0
;
;=================================================
PROC US_InitRndT randomize:word
uses si,di
public US_InitRndT
mov ax,SEG rndtable
mov es,ax
mov ax,[randomize]
or ax,ax
jne @@timeit ;if randomize is true, really random
mov dx,0 ;set to a definite value
jmp @@setit
@@timeit:
mov ah,2ch
int 21h ;GetSystemTime
and dx,0ffh
@@setit:
mov [es:rndindex],dx
ret
ENDP
;=================================================
;
; int US_RndT (void)
; Return a random # between 0-255
; Exit : AX = value
;
;=================================================
PROC US_RndT
public US_RndT
mov ax,SEG rndtable
mov es,ax
mov bx,[es:rndindex]
inc bx
and bx,0ffh
mov [es:rndindex],bx
mov al,[es:rndtable+BX]
xor ah,ah
ret
ENDP
END