124 lines
4.3 KiB
Text
124 lines
4.3 KiB
Text
/* ARM assembly Raspberry PI or android with termux */
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/* program pRandom.s */
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/* REMARK 1 : this program use routines in a include file
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see task Include a file language arm assembly
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for the routine affichageMess conversion10
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see at end of this program the instruction include */
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/* for constantes see task include a file in arm assembly */
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/************************************/
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/* Constantes */
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/************************************/
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.include "../constantes.inc"
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/*********************************/
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/* Initialized data */
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/*********************************/
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.data
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sMessResult: .asciz " @ \n"
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szCarriageReturn: .asciz "\n"
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iSeed: .int 675248
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/*********************************/
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/* UnInitialized data */
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/*********************************/
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.bss
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sZoneConv: .skip 24
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/*********************************/
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/* code section */
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/*********************************/
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.text
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.global main
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main: @ entry of program
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ldr r0,iAdriSeed
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ldr r3,[r0]
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mov r2,#5
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1:
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mov r0,r3
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bl computePseudo
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mov r3,r0
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ldr r1,iAdrsZoneConv
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bl conversion10 @ call décimal conversion
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ldr r0,iAdrsMessResult
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ldr r1,iAdrsZoneConv @ insert conversion in message
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bl strInsertAtCharInc
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bl affichageMess @ display message
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subs r2,r2,#1
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bgt 1b
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100: @ standard end of the program
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mov r0, #0 @ return code
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mov r7, #EXIT @ request to exit program
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svc #0 @ perform the system call
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iAdrszCarriageReturn: .int szCarriageReturn
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iAdrsMessResult: .int sMessResult
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iAdrsZoneConv: .int sZoneConv
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iAdriSeed: .int iSeed
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/***************************************************/
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/* compute pseudo random number */
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/***************************************************/
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/* r0 contains the number */
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computePseudo:
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push {r1-r2,lr} @ save registers
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mov r2,r0
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umull r0,r1,r2,r2
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ldr r2,idiv
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bl division32R
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ldr r2,idiv2
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bl division32R
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mov r0,r2
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pop {r1-r2,pc} @ restaur registers
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idiv: .int 1000
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idiv2: .int 1000000
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/***************************************************/
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/* division number 64 bits in 2 registers by number 32 bits */
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/***************************************************/
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/* r0 contains lower part dividende */
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/* r1 contains upper part dividende */
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/* r2 contains divisor */
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/* r0 return lower part quotient */
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/* r1 return upper part quotient */
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/* r2 return remainder */
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division32R:
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push {r3-r9,lr} @ save registers
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mov r6,#0 @ init upper upper part remainder !!
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mov r7,r1 @ init upper part remainder with upper part dividende
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mov r8,r0 @ init lower part remainder with lower part dividende
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mov r9,#0 @ upper part quotient
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mov r4,#0 @ lower part quotient
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mov r5,#32 @ bits number
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1: @ begin loop
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lsl r6,#1 @ shift upper upper part remainder
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lsls r7,#1 @ shift upper part remainder
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orrcs r6,#1
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lsls r8,#1 @ shift lower part remainder
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orrcs r7,#1
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lsls r4,#1 @ shift lower part quotient
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lsl r9,#1 @ shift upper part quotient
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orrcs r9,#1
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@ divisor sustract upper part remainder
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subs r7,r2
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sbcs r6,#0 @ and substract carry
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bmi 2f @ négative ?
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@ positive or equal
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orr r4,#1 @ 1 -> right bit quotient
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b 3f
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2: @ negative
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orr r4,#0 @ 0 -> right bit quotient
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adds r7,r2 @ and restaur remainder
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adc r6,#0
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3:
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subs r5,#1 @ decrement bit size
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bgt 1b @ end ?
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mov r0,r4 @ lower part quotient
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mov r1,r9 @ upper part quotient
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mov r2,r7 @ remainder
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100: @ function end
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pop {r3-r9,lr} @ restaur registers
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bx lr
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/***************************************************/
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/* ROUTINES INCLUDE */
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/***************************************************/
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.include "../affichage.inc"
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