135 lines
4.9 KiB
Plaintext
135 lines
4.9 KiB
Plaintext
/* ARM assembly Raspberry PI */
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/* program functMul.s */
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/* Constantes */
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.equ STDOUT, 1
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.equ WRITE, 4
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.equ EXIT, 1
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/***********************/
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/* Initialized data */
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/***********************/
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.data
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szRetourLigne: .asciz "\n"
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szMessResult: .ascii "Resultat : " @ message result
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sMessValeur: .fill 12, 1, ' '
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.asciz "\n"
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/***********************
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/* No Initialized data */
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/***********************/
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.bss
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.text
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.global main
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main:
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push {fp,lr} /* save 2 registers */
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@ function multiply
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mov r0,#8
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mov r1,#50
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bl multiply @ call function
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ldr r1,iAdrsMessValeur
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bl conversion10S @ call function with 2 parameter (r0,r1)
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ldr r0,iAdrszMessResult
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bl affichageMess @ display message
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mov r0, #0 @ return code
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100: /* end of program */
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mov r7, #EXIT @ request to exit program
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swi 0 @ perform the system call
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iAdrsMessValeur: .int sMessValeur
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iAdrszMessResult: .int szMessResult
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/******************************************************************/
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/* Function multiply */
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/******************************************************************/
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/* r0 contains value 1 */
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/* r1 contains value 2 */
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/* r0 return résult */
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multiply:
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mul r0,r1,r0
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bx lr /* return function */
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/******************************************************************/
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/* display text with size calculation */
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/******************************************************************/
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/* r0 contains the address of the message */
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affichageMess:
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push {fp,lr} /* save registres */
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push {r0,r1,r2,r7} /* save others registers */
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mov r2,#0 /* counter length */
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1: /* loop length calculation */
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ldrb r1,[r0,r2] /* read octet start position + index */
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cmp r1,#0 /* if 0 its over */
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addne r2,r2,#1 /* else add 1 in the length */
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bne 1b /* and loop */
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/* so here r2 contains the length of the message */
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mov r1,r0 /* address message in r1 */
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mov r0,#STDOUT /* code to write to the standard output Linux */
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mov r7, #WRITE /* code call system "write" */
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swi #0 /* call systeme */
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pop {r0,r1,r2,r7} /* restaur others registers */
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pop {fp,lr} /* restaur des 2 registres */
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bx lr /* return */
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/***************************************************/
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/* conversion register in string décimal signed */
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/***************************************************/
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/* r0 contains the register */
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/* r1 contains address of conversion area */
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conversion10S:
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push {fp,lr} /* save registers frame and return */
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push {r0-r5} /* save other registers */
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mov r2,r1 /* early storage area */
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mov r5,#'+' /* default sign is + */
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cmp r0,#0 /* négatif number ? */
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movlt r5,#'-' /* yes sign is - */
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mvnlt r0,r0 /* and inverse in positive value */
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addlt r0,#1
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mov r4,#10 /* area length */
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1: /* conversion loop */
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bl divisionpar10 /* division */
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add r1,#48 /* add 48 at remainder for conversion ascii */
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strb r1,[r2,r4] /* store byte area r5 + position r4 */
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sub r4,r4,#1 /* previous position */
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cmp r0,#0
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bne 1b /* loop if quotient not equal zéro */
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strb r5,[r2,r4] /* store sign at current position */
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subs r4,r4,#1 /* previous position */
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blt 100f /* if r4 < 0 end */
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/* else complete area with space */
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mov r3,#' ' /* character space */
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2:
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strb r3,[r2,r4] /* store byte */
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subs r4,r4,#1 /* previous position */
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bge 2b /* loop if r4 greather or equal zero */
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100: /* standard end of function */
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pop {r0-r5} /*restaur others registers */
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pop {fp,lr} /* restaur des 2 registers frame et return */
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bx lr
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/***************************************************/
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/* division par 10 signé */
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/* Thanks to http://thinkingeek.com/arm-assembler-raspberry-pi/*
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/* and http://www.hackersdelight.org/ */
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/***************************************************/
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/* r0 contient le dividende */
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/* r0 retourne le quotient */
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/* r1 retourne le reste */
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divisionpar10:
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/* r0 contains the argument to be divided by 10 */
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push {r2-r4} /* save autres registres */
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mov r4,r0
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ldr r3, .Ls_magic_number_10 /* r1 <- magic_number */
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smull r1, r2, r3, r0 /* r1 <- Lower32Bits(r1*r0). r2 <- Upper32Bits(r1*r0) */
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mov r2, r2, ASR #2 /* r2 <- r2 >> 2 */
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mov r1, r0, LSR #31 /* r1 <- r0 >> 31 */
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add r0, r2, r1 /* r0 <- r2 + r1 */
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add r2,r0,r0, lsl #2 /* r2 <- r0 * 5 */
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sub r1,r4,r2, lsl #1 /* r1 <- r4 - (r2 * 2) = r4 - (r0 * 10) */
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pop {r2-r4}
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bx lr /* leave function */
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.align 4
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.Ls_magic_number_10: .word 0x66666667
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