问题描述
下面是一些分部代码，我只需要帮助进行验证。该程序应该测试寄存器6和7是否大于或等于0且小于或等于268,435,455。如果它们都为0，则程序结束。但是，如果它们在参数内，则将它们添加（以16为基数），并且程序会计算代码中发生了多少次移位。例如，给定两个输入“ 13398 31898”，它将打印2。“ 268435455 1”应打印“ 7”。 该代码在用于这些验证和计数的区域中的2条注释行之间注释。寄存器1在末尾接收移位数。
目标： 测试0 如果为true，则从16开始加法。如果为false，则将它们发送到bad_int。如果它们都等于0，则程序结束。
.equ SWI_Exit,0x11 @ exit gracefully
.equ SWI_Close,0x68 @ close file
.equ SWI_Open,0x66 @ open file
.equ SWI_ReadINT,0x6c @ read integer from fd in R0 -> R0
.equ SWI_WriteINT,0x6b @ write integer in R1 to fd in R0
.equ SWI_WriteS,0x69 @ write string to stdout
.text
.global _start
_start: @ The simulator will look for "_start".
ldr r0,=filename @ R0 is the address of the file
mov r1,#0 @ R1 = 0 so we open it "read only"
swi SWI_Open @ Do the software interrupt to open the file
bcs file_not_found @ "Branch if carry set" if it did not work.
ldr r1,=file_handle @ Otherwise save the file handle for reading.
str r0,[r1] @ It is stored at "file_handle"
@ Here's the top of the "loop" in terms of reading the numbers
@ and seeing if they are not both zero. We'll put the first number
@ in R6 and the second in R7 (arbitrary choices).
loop: ldr r1,=file_handle @ Load the file handle
ldr r0,[r1] @ It goes into R0
swi SWI_ReadINT @ Ask the operating system to read one number.
mov r6,r0 @ Let's put the first number in R6 (just because)
ldr r1,=file_handle @ Load the file handle again
ldr r0,[r1]
swi SWI_ReadINT
mov r7,r0 @ Let's put the second number in R7
@ Here you will need to test to see if both numbers are zero,@ within the range in the assignment,and so on.
@ If they are,then continue,else branch down to where
@ the error prints out.
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@ Here's where you come in!
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
cmp r6,#0 @ First value less than 0?
blt bad_int @ Bad int if less than 0
cmp r6,#268,455 @ First value greater than 268,455?
bgt bad_int @ Bad int if greater than 268,455
cmp r7,#0 @ Second value greater than 0
blt bad_int @ Bad int if less than 0
cmp r6,455
cmp r6,r7 @ Are both equal to zero?
beq 0,end
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@ Put your answer into R1 so that we can print it
mov r0,#1 @ stdout
swi SWI_WriteINT
ldr r1,=newline
swi SWI_WriteS
b loop @ Next set of numbers please.
bad_int:
mov r0,#1 @ Stdout
ldr r1,=bad_string @ Write the bad data string
swi SWI_WriteS
b loop
end_of_file:
ldr r0,=file_handle
ldr r0,[r0]
swi SWI_Close
swi SWI_Exit
file_not_found:
mov r0,#1 @ In the case where we Could
ldr r1,=in_file_error @ not open the file,of course
swi SWI_WriteS @ there is no need to close it.
swi SWI_Exit @ So bail out.
@ ============================================================
@ Data
@ ============================================================
.data
@ Any "word" must be aligned on four bytes
.align 4
file_handle: .word 0x00
@ Strings can be aligned anywhere.
filename: .asciz "CARRY.TXT"
in_file_error: .asciz "No such file???\n"
bad_string: .asciz "The file contains invalid data!\n"
newline: .asciz "\n"
解决方法
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