Question

我正在尝试在下面的ARM程序中填充我的数组i，程序在使用.global main .func main main: MOV R3, #0 @ initialze index variable BL writeloop @ call write function BL readloop @call read function (prints a) writeloop: CMP R3, #10 @ check to see if we are done iterating BEQ writedone @ exit loop if done LDR R1, =a @ get address of a LSL R2, R3, #2 @ multiply index*4 to get array offset ADD R2, R1, R2 @ R2 now has the element address BL _scanf MOV R4,R0 STR R4, [R2] @ write input to a[i] ADD R3, R3, #1 @ increment index B writeloop @ branch to next loop iteration writedone: MOV R3, #0 @ initialze index variable readloop: CMP R3, #10 @ check to see if we are done iterating BEQ readdone @ exit loop if done LDR R1, =a @ get address of a LSL R2, R3, #2 @ multiply index*4 to get array offset ADD R2, R1, R2 @ R2 now has the element address LDR R1, [R2] @ read the array at address PUSH {R3} @ backup register before printf PUSH {R1} @ backup register before printf PUSH {R2} @ backup register before printf MOV R2, R1 @ move array value to R2 for printf MOV R1, R3 @ move array index to R1 for printf BL _printf @ branch to print procedure with return POP {R2} @ restore register POP {R1} @ restore register POP {R3} @ restore register ADD R3, R3, #1 @ increment index B readloop @ branch to next loop iteration readdone: MOV R3,#0 @reset counter (i) _scanf: PUSH {LR} @ store the return address PUSH {R1} @ backup regsiter value LDR R0, =format_str @ R0 contains address of format string SUB SP, SP, #4 @ make room on stack MOV R1, SP @ move SP to R1 to store entry on stack BL scanf @ call scanf LDR R0, [SP] @ load value at SP into R0 ADD SP, SP, #4 @ remove value from stack POP {R1} @ restore register value POP {PC} @ restore the stack pointer and return _exit: MOV R7, #4 @ write syscall, 4 MOV R0, #1 @ output stream to monitor, 1 MOV R2, #21 @ print string length LDR R1, =exit_str @ string at label exit_str: SWI 0 @ execute syscall MOV R7, #1 @ terminate syscall, 1 SWI 0 @ execute syscall _printf: PUSH {LR} @ store the return address LDR R0, =printf_str @ R0 contains formatted string address BL printf @ call printf POP {PC} @ restore the stack pointer and return .data format_str: .asciz "%d" .balign 4 a: .skip 40 printf_str: .asciz "a[%d] = %d\n" exit_str: .ascii "Terminating program.\n"值填充时没有任何问题，但我现在尝试使用用户输入填充索引。我实现的_scanf没有任何问题，因为我之前在许多程序中使用它（在许多其他程序中称为它），但在这个程序中，它假设停在10但它没有。它继续前进，我不知道问题出在哪里。

<script>    
var x= <%= globalXInCS %>
</script>

Answer 1

DStream[String] transformed

您可能需要查看http://infocenter.arm.com/help/topic/com.arm.doc.ihi0042f/IHI0042F_aapcs.pdf第5章第14页。

ARM：如何从用户输入正确填充数组？

1 个答案: