【发布时间】：2017-05-30 21:57:49
【问题描述】：
我正在研究 FP IEEE-754 到 MASM 组装的 StrDec。它工作正常，尽管我花了一些时间来解决这个问题，但我不确定如何在逗号后添加更多数字 - 现在有两个，比如123.46，但我需要123.456789。我想我确实需要一个计数器来处理我的额外位，但我得到access violation，同时在逗号后添加额外数字并增加字节数。
.data
CaptionOut BYTE "Result: ", 0
temp_bcd dt ?
szdecimal db 32 dup(0)
MyNum REAL10 123.456789
.code
main PROC
; FPU to DecStr
fld MyNum
pushd 100 ;use the stack as storage for this value
fimul dword ptr[esp] ;converts 2 decimal places as 2 more integer digits
fbstp temp_bcd ;store the packed BCD integer value
pop eax ;clean the stack of the pushed 100
; ESI will be used for pointing to the packed BCD
; EDI will be used for pointing to the decimal string
push esi
push edi
lea esi,temp_bcd+9 ;point to the most significant byte
lea edi,szdecimal ;point to the start of the decimal string buffer
xor eax,eax
fwait ;to ascertain that the transfer of the
;packed BCD is completed
mov al,[esi] ;get the byte with the sign code
dec esi ;decrement to next most significant byte
or al,al ;for checking the sign bit
jns @F ;jump if no sign bit
mov al,"-" ;the value is negative
stosb ;insert the negative sign
@@:
; The next 8 bytes (in this example) will contain the integer digits
; and the least significant byte will then contain the 2 decimal digits.
; No leading 0 will be included in the integer portion
; unless it would be the only integer digit.
mov ecx,8 ;number of bytes to process for integer digits
@@:
mov al,[esi] ;get the next byte
dec esi ;adjust the pointer to the next one
or al,al ;for checking if it is 0
jnz @F ;the starting integer digit is now in AL
dec ecx ;adjust the counter of integer bytes
jnz @B ;continue searching for the first integer digit
; If the loop terminates with ECX=0, the integer portion would be 0.
; A "0" character must be inserted before processing the decimal digits
mov al,"0" ;the ASCII 0
stosb ;insert it
mov al,[esi] ;get the byte containing the decimal digits
jmp decimal_digits
@@:
; The first integer byte must be checked to determine
; if it contains 1 or 2 integer digits
test al,0f0h ;test if the H.O. nibble contains a digit
jz int_digit2 ;if not, process only the L.O. nibble
int_digit1:
ror ax,4 ;puts the H.O. nibble in the L.O. nibble position
;and saves the L.O. nibble in AH
add al,30h ;convert it to ASCII character
stosb ;store this character
shr ax,12 ;restores the L.O. nibble in AL
;and also resets the other bits of AX
int_digit2:
add al,30h ;convert it to ASCII character
stosb ;store this character
mov al,[esi] ;get next byte
dec esi ;adjust the pointer to the next one
dec ecx ;adjust the counter of integer bytes
jnz int_digit1 ;continue processing the integer bytes
decimal_digits:
mov byte ptr [edi],"." ;insert the preferred decimal delimiter
inc edi
; Also, if the number of required decimal digits is not even, the code
; would have to be altered to insert the decimal delimiter at the
; proper location.
ror ax,4 ;puts the H.O. nibble in the L.O. nibble position
;and saves the L.O. nibble in AH
add al,30h ;convert it to ASCII character
stosb ;store this character
shr ax,12 ;restores the L.O. nibble in AL
;and also resets the other bits of AX
add al,30h ;convert it to ASCII character
stosw ;store this character + the terminating 0
INVOKE MessageBoxA, 0, ADDR szdecimal, ADDR CaptionOut, 0
INVOKE ExitProcess,0
main ENDP
END main
感谢任何帮助或想法！
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