我正在X86 AT&类赋值的T程序集。我单独测试了所有的函数，它们完全按照预期工作，但出于某种原因，我在标题中几乎每一行代码都收到了警告。由于各个函数都是在放在自己的文件中编译的，除了函数之外什么都没有，所以我真的不明白这里有什么错。请帮忙。
我是在14.04 Ubuntu上写的。
gcc -m32 -c pstring.s
pstring.s: Assembler messages:
pstring.s: Warning: end of file in string; '"' inserted
pstring.s:3: Warning: unterminated string; newline inserted
pstring.s:4: Warning: unterminated string; newline inserted
pstring.s:5: Warning: unterminated string; newline inserted
pstring.s:6: Warning: unterminated string; newline inserted
pstring.s:7: Warning: unterminated string; newline inserted
pstring.s:8: Warning: unterminated string; newline inserted
pstring.s:9: Warning: unterminated string; newline inserted
pstring.s:10: Warning: unterminated string; newline inserted
pstring.s:11: Warning: unterminated string; newline inserted
pstring.s:12: Warning: unterminated string; newline inserted
pstring.s:13: Warning: unterminated string; newline inserted
pstring.s:14: Warning: unterminated string; newline inserted
pstring.s:15: Warning: unterminated string; newline inserted
pstring.s:16: Warning: unterminated string; newline inserted
pstring.s:17: Warning: unterminated string; newline inserted
pstring.s:18: Warning: unterminated string; newline inserted
pstring.s:19: Warning: unterminated string; newline inserted
pstring.s:20: Warning: unterminated string; newline inserted
pstring.s:21: Warning: unterminated string; newline inserted
pstring.s:22: Warning: unterminated string; newline inserted
pstring.s:23: Warning: unterminated string; newline inserted
pstring.s:24: Warning: unterminated string; newline inserted
pstring.s:25: Warning: unterminated string; newline inserted
pstring.s:26: Warning: unterminated string; newline inserted
pstring.s:27: Warning: unterminated string; newline inserted
pstring.s:28: Warning: unterminated string; newline inserted
pstring.s:29: Warning: unterminated string; newline inserted
pstring.s:30: Warning: unterminated string; newline inserted
pstring.s:31: Warning: unterminated string; newline inserted
pstring.s:32: Warning: unterminated string; newline inserted
pstring.s:33: Warning: unterminated string; newline inserted
pstring.s:34: Warning: unterminated string; newline inserted
pstring.s:35: Warning: unterminated string; newline inserted
pstring.s:36: Warning: unterminated string; newline inserted
pstring.s:37: Warning: unterminated string; newline inserted
pstring.s:38: Warning: unterminated string; newline inserted
pstring.s:39: Warning: unterminated string; newline inserted
pstring.s:40: Warning: unterminated string; newline inserted
pstring.s:41: Warning: unterminated string; newline inserted
pstring.s:42: Warning: unterminated string; newline inserted
pstring.s:43: Warning: unterminated string; newline inserted
pstring.s:44: Warning: unterminated string; newline inserted
pstring.s:45: Warning: unterminated string; newline inserted
pstring.s:46: Warning: unterminated string; newline inserted
pstring.s:47: Warning: unterminated string; newline inserted
pstring.s:48: Warning: unterminated string; newline inserted
pstring.s:49: Warning: unterminated string; newline inserted
pstring.s:50: Warning: unterminated string; newline inserted
pstring.s:51: Warning: unterminated string; newline inserted
pstring.s:52: Warning: unterminated string; newline inserted
pstring.s:53: Warning: unterminated string; newline inserted
pstring.s:54: Warning: unterminated string; newline inserted
pstring.s:55: Warning: unterminated string; newline inserted
pstring.s:56: Warning: unterminated string; newline inserted
pstring.s:57: Warning: unterminated string; newline inserted
pstring.s:58: Warning: unterminated string; newline inserted
pstring.s:59: Warning: unterminated string; newline inserted
pstring.s:60: Warning: unterminated string; newline inserted
pstring.s:61: Warning: unterminated string; newline inserted
pstring.s:62: Warning: unterminated string; newline inserted
pstring.s:63: Warning: unterminated string; newline inserted
pstring.s:64: Warning: unterminated string; newline inserted
pstring.s:65: Warning: unterminated string; newline inserted
pstring.s:66: Warning: unterminated string; newline inserted
pstring.s:67: Warning: unterminated string; newline inserted
pstring.s:68: Warning: unterminated string; newline inserted
pstring.s:69: Warning: unterminated string; newline inserted
pstring.s:70: Warning: unterminated string; newline inserted
pstring.s:71: Warning: unterminated string; newline inserted
pstring.s:72: Warning: unterminated string; newline inserted
pstring.s:73: Warning: unterminated string; newline inserted
pstring.s:74: Warning: unterminated string; newline inserted
pstring.s:75: Warning: unterminated string; newline inserted
pstring.s:76: Warning: unterminated string; newline inserted
pstring.s:77: Warning: unterminated string; newline inserted
pstring.s:78: Warning: unterminated string; newline inserted
pstring.s:79: Warning: unterminated string; newline inserted
pstring.s:80: Warning: unterminated string; newline inserted
pstring.s:81: Warning: unterminated string; newline inserted
pstring.s:82: Warning: unterminated string; newline inserted
pstring.s:83: Warning: unterminated string; newline inserted
pstring.s:84: Warning: unterminated string; newline inserted
pstring.s:85: Warning: unterminated string; newline inserted
pstring.s:86: Warning: unterminated string; newline inserted
pstring.s:87: Warning: unterminated string; newline inserted
pstring.s:88: Warning: unterminated string; newline inserted
pstring.s:89: Warning: unterminated string; newline inserted
pstring.s:90: Warning: unterminated string; newline inserted
pstring.s:91: Warning: unterminated string; newline inserted
pstring.s:92: Warning: unterminated string; newline inserted
pstring.s:93: Warning: unterminated string; newline inserted
pstring.s:94: Warning: unterminated string; newline inserted
pstring.s:95: Warning: unterminated string; newline inserted
pstring.s:96: Warning: unterminated string; newline inserted
pstring.s:97: Warning: unterminated string; newline inserted
pstring.s:98: Warning: unterminated string; newline inserted
pstring.s:99: Warning: unterminated string; newline inserted
pstring.s:100: Warning: unterminated string; newline inserted
pstring.s:101: Warning: unterminated string; newline inserted
pstring.s:102: Warning: unterminated string; newline inserted
pstring.s:103: Warning: unterminated string; newline inserted
pstring.s:104: Warning: unterminated string; newline inserted
pstring.s:105: Warning: unterminated string; newline inserted
pstring.s:106: Warning: unterminated string; newline inserted
pstring.s:107: Warning: unterminated string; newline inserted
pstring.s:108: Warning: unterminated string; newline inserted
pstring.s:109: Warning: unterminated string; newline inserted
pstring.s:110: Warning: unterminated string; newline inserted
pstring.s:111: Warning: unterminated string; newline inserted
pstring.s:112: Warning: unterminated string; newline inserted
pstring.s:113: Warning: unterminated string; newline inserted
pstring.s:114: Warning: unterminated string; newline inserted
pstring.s:115: Warning: unterminated string; newline inserted
pstring.s:116: Warning: unterminated string; newline inserted
pstring.s:117: Warning: unterminated string; newline inserted
pstring.s:118: Warning: unterminated string; newline inserted
pstring.s:119: Warning: unterminated string; newline inserted
pstring.s:120: Warning: unterminated string; newline inserted
pstring.s:121: Warning: unterminated string; newline inserted
pstring.s:122: Warning: unterminated string; newline inserted
pstring.s:123: Warning: unterminated string; newline inserted
pstring.s:124: Warning: unterminated string; newline inserted
pstring.s:125: Warning: unterminated string; newline inserted
pstring.s:126: Warning: unterminated string; newline inserted
pstring.s:127: Warning: unterminated string; newline inserted
pstring.s:128: Warning: unterminated string; newline inserted
pstring.s:129: Warning: unterminated string; newline inserted
pstring.s:130: Warning: unterminated string; newline inserted
pstring.s:131: Warning: unterminated string; newline inserted
pstring.s:132: Warning: unterminated string; newline inserted
pstring.s:133: Warning: unterminated string; newline inserted
pstring.s:134: Warning: unterminated string; newline inserted
pstring.s:135: Warning: unterminated string; newline inserted
pstring.s:136: Warning: unterminated string; newline inserted
pstring.s:137: Warning: unterminated string; newline inserted
pstring.s:138: Warning: unterminated string; newline inserted
pstring.s:139: Warning: unterminated string; newline inserted
pstring.s:140: Warning: unterminated string; newline inserted
pstring.s:141: Warning: unterminated string; newline inserted
pstring.s:142: Warning: unterminated string; newline inserted
pstring.s:143: Warning: unterminated string; newline inserted
pstring.s:144: Warning: unterminated string; newline inserted
pstring.s:145: Warning: unterminated string; newline inserted
pstring.s:146: Warning: unterminated string; newline inserted
pstring.s:147: Warning: unterminated string; newline inserted
pstring.s:148: Warning: unterminated string; newline inserted
pstring.s:149: Warning: unterminated string; newline inserted
pstring.s:150: Warning: unterminated string; newline inserted
pstring.s:151: Warning: unterminated string; newline inserted
pstring.s:152: Warning: unterminated string; newline inserted
pstring.s:153: Warning: unterminated string; newline inserted
pstring.s:154: Warning: unterminated string; newline inserted
pstring.s:155: Warning: unterminated string; newline inserted
pstring.s:156: Warning: unterminated string; newline inserted
pstring.s:157: Warning: unterminated string; newline inserted
pstring.s:158: Warning: unterminated string; newline inserted
pstring.s:159: Warning: unterminated string; newline inserted
pstring.s:160: Warning: unterminated string; newline inserted
pstring.s:161: Warning: unterminated string; newline inserted
pstring.s:162: Warning: unterminated string; newline inserted
pstring.s:163: Warning: unterminated string; newline inserted
pstring.s:164: Warning: unterminated string; newline inserted
pstring.s:165: Warning: unterminated string; newline inserted
pstring.s:166: Warning: unterminated string; newline inserted
pstring.s:167: Warning: unterminated string; newline inserted
pstring.s:168: Warning: unterminated string; newline inserted
pstring.s:169: Warning: unterminated string; newline inserted
pstring.s:170: Warning: unterminated string; newline inserted
pstring.s:171: Warning: unterminated string; newline inserted
pstring.s:172: Warning: unterminated string; newline inserted
pstring.s:173: Warning: unterminated string; newline inserted
pstring.s:174: Warning: unterminated string; newline inserted
pstring.s:175: Warning: unterminated string; newline inserted
pstring.s:176: Warning: unterminated string; newline inserted
pstring.s:177: Warning: unterminated string; newline inserted
pstring.s:178: Warning: unterminated string; newline inserted
pstring.s:179: Warning: unterminated string; newline inserted
pstring.s:180: Warning: unterminated string; newline inserted
pstring.s:181: Warning: unterminated string; newline inserted
pstring.s:182: Warning: unterminated string; newline inserted
pstring.s:183: Warning: unterminated string; newline inserted
pstring.s:184: Warning: unterminated string; newline inserted
pstring.s:185: Warning: unterminated string; newline inserted
pstring.s:186: Warning: unterminated string; newline inserted
pstring.s:187: Warning: unterminated string; newline inserted
pstring.s:188: Warning: unterminated string; newline inserted
pstring.s:189: Warning: unterminated string; newline inserted
pstring.s:190: Warning: unterminated string; newline inserted
pstring.s:191: Warning: unterminated string; newline inserted
pstring.s:192: Warning: unterminated string; newline inserted
pstring.s:193: Warning: unterminated string; newline inserted
pstring.s:194: Warning: unterminated string; newline inserted
pstring.s:195: Warning: unterminated string; newline inserted
pstring.s:196: Warning: unterminated string; newline inserted
pstring.s:197: Warning: unterminated string; newline inserted
pstring.s:198: Warning: unterminated string; newline inserted
pstring.s:199: Warning: unterminated string; newline inserted
pstring.s:200: Warning: unterminated string; newline inserted
pstring.s:201: Warning: unterminated string; newline inserted
pstring.s:202: Warning: unterminated string; newline inserted
pstring.s:203: Warning: unterminated string; newline inserted
pstring.s:204: Warning: unterminated string; newline inserted
pstring.s:205: Warning: unterminated string; newline inserted
pstring.s:206: Warning: unterminated string; newline inserted
pstring.s:207: Warning: unterminated string; newline inserted
pstring.s:208: Warning: unterminated string; newline inserted
pstring.s:209: Warning: unterminated string; newline inserted
pstring.s:210: Warning: unterminated string; newline inserted
pstring.s:211: Warning: unterminated string; newline inserted
pstring.s:212: Warning: unterminated string; newline inserted
pstring.s:213: Warning: unterminated string; newline inserted
pstring.s:214: Warning: unterminated string; newline inserted
pstring.s:215: Warning: unterminated string; newline inserted
pstring.s:216: Warning: unterminated string; newline inserted
pstring.s:217: Warning: unterminated string; newline inserted
pstring.s:218: Warning: unterminated string; newline inserted
pstring.s:219: Warning: unterminated string; newline inserted
pstring.s:220: Warning: unterminated string; newline inserted
pstring.s:221: Warning: unterminated string; newline inserted
pstring.s:222: Warning: unterminated string; newline inserted
pstring.s:223: Warning: unterminated string; newline inserted
pstring.s:224: Warning: unterminated string; newline inserted
pstring.s:225: Warning: unterminated string; newline inserted
pstring.s:226: Warning: unterminated string; newline inserted
pstring.s:227: Warning: unterminated string; newline inserted
pstring.s:228: Warning: unterminated string; newline inserted
pstring.s:229: Warning: unterminated string; newline inserted
pstring.s:230: Warning: unterminated string; newline inserted
pstring.s:231: Warning: unterminated string; newline inserted
pstring.s:232: Warning: unterminated string; newline inserted
pstring.s:233: Warning: unterminated string; newline inserted
pstring.s:234: Warning: unterminated string; newline inserted
pstring.s:235: Warning: unterminated string; newline inserted
321123242 Nikolay Babkin
.section .rodata
error: .string "invalid input!n' # error message.
.text
.global pstrlen #receives a pointer to a pstring as argument.
.type pstrlen, @function #returns the length as a byte.
pstrlen:
pushl %ebp #save old FP.
movl %esp, %ebp #set new FP.
movl 8(%ebp), %eax #retrieve pointer to pstring.
movb (%eax), %al #copy the first byte of the argument into %al
movzbl %al, %eax #Zero-fill the other 3 bytes of the register.
movl %ebp, %esp #restore the old stack pointer - release all used memory.
popl %ebp #restore old frame pointer (the caller function frame)
ret #return to caller function
.global replaceChar #receives a pointer to a pstring, a oldChar byte and a newChar byte as arguments.
.type replaceChar, @function #replaces all oldChars with newChars and returns the pointer to the pstring
replaceChar:
pushl %ebp #save old FP
movl %esp, %ebp #set new FP
pushl %ebx #save %ebx on stack
movl 8(%ebp), %eax #get the pstring pointer from the stack.
movb (%eax), %bh #retrieved the len of the pstring
addl $1, %eax #align the pointer to point to the string itself
movl 12(%ebp), %ecx #get the oldChar argument.
movb %cl, %dl #store oldChar in %dl
movl 16(%ebp), %ecx #get the newChar argument.
movb %cl, %dh #store newChar in %dh
movb $0, %bl #initialize count register to 1.
rcTEST:
cmpb %bh, %bl #Test
je rcDONE #if Test: goto done
rcLOOP: #loop label
cmpb %dl, (%eax) #compare the current byte to the oldChar byte
je rcCHANGE #jump to change the oldChar.
rcINCREMENT: #label for incrementing the current char and the count variable.
add $1, %bl #increment the count
add $1, %eax #increment the string pointer one byte.
jmp rcTEST #Don't want no infinite loops causing segmentation faults, do we?
rcCHANGE:
movb %dh, (%eax) #overwrite the oldChar with a newChar
jmp rcINCREMENT #move on with the loop mechanism
rcDONE:
mov 8(%ebp), %eax #set return value to be the pstring pointer.
popl %ebx #restore %ebx register.
movl %ebp, %esp #restore the old stack pointer - release all used memory.
popl %ebp #restore old frame pointer (the caller function frame)
ret #return to caller function
.global pstrijcpy
.type pstrijcpy, @function
pstrijcpy:
pushl %ebp #save old FP
movl %esp, %ebp #set new FP
#using eax, ebx, ech, edx,
pushl %ebx #back %ebx up.
movl 16(%ebp), %eax #the dword with i
movb %al, %bl #store i in %bl
movl 20(%ebp), %eax #the dword with j
movb %al, %bh #store j in %bh
movl 8(%ebp), %eax #initialize eax to dst ptr.
movb (%eax), %dh #%dh <- dst.len
addl $1, %eax #advance %eax by one byte to the string
movl 12(%ebp), %ecx #initialize ecx to src ptr.
mov (%ecx), %dl #%dl <- src.len
addl $1, %ecx #advance %ecx by one byte to the string
cmpb %dl, %bl #i-src.len
jg cpyERROR #if >: goto error
cmp %dl, %bh #j-src.len
jg cpyERROR #if >: goto error
cmpb %dh, %bl #i-dst.len
jg cpyERROR #if >: goto error
cmp %dh, %bh #j-dst.len
jg cpyERROR #if >: goto error
#now I will add i to the pointers that point to the strings.
push %edx #back edx up
movzbl %bl, %edx #apparently I can use 'movl %bl, %eax', so I did this.
addl %edx, %eax #advance dst to ith character
addl %edx, %ecx #advance src to ith character
popl %edx #restore edx
cpyTEST:
cmpb %bh, %bl #compare i with j
jg cpyDONE #once i is greater than j, we are done.
cpyLOOP:
movb (%ecx), %dl #Since I already checked that i and j <= the lengths, I can use them
movb %dl, (%eax) #Move byte from src to dst.
addl $1, %ecx #Increment src to next byte
addl $1, %eax #Increment dst to next byte
addl $1, %ebx #Increment i by 1.
jmp cpyTEST #goto test
cpyERROR: #don't need to back registers up.
pushl $error #push the message to be printed.
call printf #use printf to print error message
cpyDONE:
popl %ebx #restore %ebx
movl 8(%ebp), %eax #set return value to be dst pointer.
movl %ebp, %esp #restore the old stack pointer - release all used memory.
popl %ebp #restore old frame pointer (the caller function frame)
ret #return to caller function
.global swapCase #swaps the cases of the string.
.type swapCase, @function
swapCase:
pushl %ebp #save old FP
movl %esp, %ebp #set new FP
movl 8(%ebp), %eax #get pointer to pstring
movb (%eax), %cl #get length of pstring
addl $1, %eax #move pointer to string itself
scLTEST: #loop condition.
cmpb $0, %cl #compare length with 0
je scDONE #if length is zero, goto done
jmp scLOOP #else: goto loop
scLOOP:
cmpb $97, (%eax) #compares first byte of string with 'a'.
jge scTRYLOWER #byte is lowercase-possible.
cmpb $90, (%eax) #compares first byte of string with 'Z'.
jle scTRYUPPER #byte is uppercase-possible.
jmp scINC #byte is between 65 and 97, so not a letter.
scTRYUPPER: #checking if byte is really upper-case.
cmpb $65, (%eax) #compare byte with 'A'.
jge scCHANGETOLOWER #if byte is 'A' or after, it is upper-case, so change to lower-case.
jmp scINC #otherwise, it is below 'A' and is thus not a letter.
scTRYLOWER:
cmpb $122, (%eax) #compare byte with 'z'.
jle scCHANGETOUPPER #if it is before or at 'z', it is a lower-case letter.
jmp scINC #otherwise, it is over 'z' and not a letter.
scCHANGETOUPPER:
subb $32, (%eax) #reduce the byte from range [97,122] to [65,90]
jmp scINC
scCHANGETOLOWER:
addb $32, (%eax) #increase the byte to range [97,122] from [65,90]
#jmp scINC #for now, the jump is not necessary since the increment stage is already after it.
scINC:
addl $1, %eax #increment %eax to next byte
decb %cl #decrement counter
jmp scLTEST #end current loop iteration
scDONE:
movl 8(%ebp), %eax #set return value to pointer to pstring.
movl %ebp, %esp #restore old stack pointer
popl %ebp #restore old FP
ret #return to caller function
.global pstrijcmp #compares pstring1 and pstring 2 in range i to j.
.type pstrijcmp, @function #returns -1 if pstring1 < pstring2, 0 if equal and 1 if greater. -2 is error value.
pstrijcmp:
pushl %ebp #save old FP
movl %esp, %ebp #set new FP
pushl %ebx #back %ebx up.
movl 16(%ebp), %eax #retrieve the dword with i.
movb %al, %ch #set %ch to be i.
movl 20(%ebp), %eax #retrieve the dword with j.
movb %al, %cl #set %cl to be j.
movl 8(%ebp), %eax #set pstring1ptr into eax.
movl 12(%ebp), %edx #set pstring2ptr into edx.
cmpb (%eax), %ch #i-str1.len
jg cmpERROR #if i>len: goto error
cmp (%eax), %cl #j-str1.len
jg cmpERROR #if jlen>: goto error
cmpb (%edx), %ch #i-str2.len
jg cmpERROR #if i>len2: goto error
cmp (%edx), %cl #j-str2.len
jg cmpERROR #if j>len2: goto error
incl %eax #increment eax to get past the length byte
incl %edx #increment edx to get past the length byte
cmpTEST:
cmpb %cl, %ch #compare i with j
jg cmpPREDONE #goto done once i>j
#jmp cmpLOOP #else: goto loop
cmpLOOP:
movb (%eax), %bl #take current str1 byte into %bl
cmpb %bl, (%edx) #compare %bl with first %edx byte
je cmpINC #if same: increment phase.
jl cmpLESS #str1 is before str2 lexicographically.
movl $1, %eax #set return value to 1.
jmp cmpDONE #done.
cmpLESS:
movl $-1, %eax #set return value to -1
jmp cmpDONE #done
cmpINC:
incl %eax #increment str1 pointer.
incl %edx #increment str2 pointer.
incb %ch #i++
jmp cmpTEST #current loop iteration is over.
cmpERROR: #don't need to back registers up.
pushl $error #push the message to be printed.
call printf #use printf to print error message
movl $-2, %eax #set return value to -2
jmp cmpDONE
cmpPREDONE:
movl $0, %eax #set return value to 0.
cmpDONE:
popl %ebx #restore old %ebx
movl %ebp, %esp #restore old stack pointer
popl %ebp #restore old FP
ret #return to caller function
错误出现在第3行，如消息所示。您有"string'而不是"string"。（注意最后的引号）。
此外，像cmpb指令上的"Test"这样的注释也是无用的。您应该评论为什么代码做它所做的事情，或者至少涉及哪些数据。我知道写一些读起来像insn-ref手册的评论很诱人，但不要。
movb $0, %bl #initialize count register to 1.特别有趣。
此外，将代码缩进到比标签多一级的位置，使它们脱颖而出。
x86 wiki有很多不错的链接，顺便说一句，