www.pudn.com > 44B0X_uCOS276.rar > rand.s

	AREA	|subr|, CODE, READONLY 
 
	EXPORT  randomnumber 
randomnumber 
; on exit: 
;	a1 = low 32-bits of pseudo-random number 
;   a2 = high bit (if you want to know it) 
    LDR     ip, |seedpointer| 
    LDMIA   ip, {a1, a2} 
    TST     a2, a2, LSR#1           ; to bit into carry 
    MOVS    a3, a1, RRX             ; 33-bit rotate right 
    ADC     a2, a2, a2              ; carry into LSB of a2 
	ADC     a2, a2, a2              ; carry into LSB of a2 
    EOR     a3, a3, a1, LSL#12      ; (involved!) 
    EOR     a1, a3, a3, LSR#20      ; (similarly involved!) 
    STMIA   ip, {a1, a2} 
 
    MOV     pc, lr 
 
|seedpointer| 
	DCD     seed 
 
    AREA    |Random$$data|, DATA 
 
    EXPORT  seed 
seed 
	DCD     &55555555 
    DCD     &55555555      
        
    END