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rnd.asm
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Assembly Source File
|
1987-03-23
|
721b
|
40 lines
*\
* :ts=8
* Yet Another random number generator. By Leo Schwab.
* Based on an idea posted on the USENET (Thanks, Sam Dicker!)
* For the Manx assembler.
*
* Calling convention:
* short rnd (range);
* short range;
*
* 8606.30
*/
public _rnd
_rnd lea rndseed,a0 ; Get address of seed
move.w 4(sp),d1 ; Get range argument
tst.w d1
ble.s setseed ; Go reset seed
move.l (a0),d0 ; Get seed
ADD.L D0,D0
BHI.S over
EORI.L #$1D872B41,D0
over
move.l d0,(a0) ; Save new seed
andi.l #$ffff,d0 ; Coerce into word
divu d1,d0 ; Divide by range
swap d0 ; and get remainder (modulus)
rts
setseed neg.w d1 ; Probably don't need this
move.l d1,(a0)
rts
dseg
rndseed dc.l 0
cseg