所以我从gcc调用ARM中的printf函数从寄存器中打印出来。
这是我的代码：
.global main
.global printf
.global fopen
.global fclose
.global fgetc
main:
@ Open File
PUSH {R1} @ Push address of R1 onto stack
LDR R0, [R1, #0x04] @ Get argv[1] from stack to R0
LDR R1, =r @ Load address of file open format (read)
BL fopen @ Open file
LDR R1, =fin @ Load address of file in to R1
STR R0, [R1] @ Store contents of R1 into R0
@ Setup array
LDR R4, =ch_array @ Array address
MOV R3, #0 @ Array index
BL loopFile
BL printArray
@ Loop through the file
loopFile:
LDR R1, =fin @ Load R1 with address of file in
LDR R0, [R1] @ Load R0 with pointer? of R1
BL fgetc @ Get next character from file into R0?
CMP R0, #-1 @ Check for end of file
BEQ endl @ Close file
@ get index from character (fgetc)
/*
Assuming the base address is in R4 (my array), the ascii is in R0
from the file input into R0: increment the word in memory at
the address 'R4 + (R0 * 4)'. *4 because each word is 4 bytes.
*/
LSL R0, R0, #2
LDR R1, [R4, R0]
ADD R1, R1, #1
STR R1, [R4, R0]
B loopFile @ Run loop again
@ Close the file
endl:
LDR R1, =fin @ Load R1 with address of file in
LDR R0, [R1] @ Load R0 with pointer? of R1
BL fclose @ Close the file
printArray:
CMP R3, #ARRAY_MAX @ while (i < ARRAY_MAX)
BEQ _exit @ Exit if max
@ Check if value of the array at index i where
@ (i = character number) is 0, if so then skip it
@ else print it
@ R3 counter of array
@ R4 array address
LDR R0, =printa @ Load print format
MOV R1, R3 @ Store character value (index of array) in R1
LDR R2, [R4, R3] @ Load count of index R3
CMP R2, #0 @ Check if count is 0
BEQ printArray @ If count is 0, skip
BL printf @ Else print
ADD R3, R3, #1 @ Increment R3 ('i')
B printArray @ Loop next iteration of array
@ End program
_exit:
MOV R7, #1
MOV R0, #0
SWI 0
.data
.equ ARRAY_MAX, 255
ch_array:
.rept ARRAY_MAX @For all elements in array, repeat:
.word 0x00 @Initialize to 0
.endr @End repetition
fin: .word 0x00
printa: .asciz "%d : %d\n"
r: .asciz "r"
space: .asciz " "
nl: .asciz "\n"
但是，屏幕上没有任何内容。没有错误或任何错误，没有分段错误。我正确地加载了这些参数，所以我似乎无法弄清楚我哪里出错！
由于