## LSU EE 4720 Computer Architecture Spring 2011 # # Classroom example for review of MIPS: Convert int to hex string. .data msg: .asciiz "The value of 0x%/s4/x is %/a1/s\n" str: .align 4 .space 12 values: .word 1234 .word 0x1234 .word 0xa9 .word 0x0 .word 0xf .word 0xf00d .word -1 ############################################################################### # ## Test Code # # This code calls the hex to string routine multiple times using # data appearing above. # .text .globl __start __start: la $s2, values addi $s3, $0, -1; MLOOP: lw $a0, 0($s2) la $a1, str lui $t0, 0x2020 ori $t0, $t0, 0x2020 sw $t0, 0($a1) sw $t0, 4($a1) sw $t0, 8($a1) sb $0, 11($a1) jal itos addi $a2, $0, 10 lw $s4, 0($s2) la $a1, str la $a0, msg addi $v0, $0, 11 syscall addi $s2, $s2, 4 bne $s4, $s3 MLOOP li $v0, 10 syscall nop ############################################################################### # # Int to Hex String # itos: ## Register Usage # # $a0: CALL VALUE: Integer to convert # $a1: Address of storage. # Initialized as null-terminated string of blanks. # $a2: Length of storage. # # RETURN: # Write storage with hex representation of $a0. # # NOTE: Registers $a0-$a4 and $t0-$t7 can be modified. # NOTE: 'a' = 97, 'z' = 122, 'a' - 'A' = 32 # NOTE: '0' = 48 = 0x30 addi $t0, $0, 48 sb $t0, 0($a1) addi $t0, $0, 120 sb $t0, 1($a1) addi $t1, $a1, 9 LOOP: andi $t0, $a0, 0xf slti $t2, $t0, 10 bne $t2, $0, DIGIT addi $t0, $t0, 48 addi $t0, $t0, 39 DIGIT: sb $t0, 0($t1) srl $a0, $a0, 4 bne $a0, $0, LOOP addi $t1, $t1, -1 DONE: jr $ra nop