问题描述
*我似乎找不到解决方法来修复我的chkvar中的代码（lb $ t3，tokArray + 0（$ s5））并不断出现错误：第77行：运行时异常位于0x004000a8：地址超出范围0x10400004
开始：执行由于错误而终止。*
.data
saveReg: .word 0:10 # extra register space!
#NULL or 0 in tokArray prematurely terminates dumping
#tokArray.Use blanks instead.
TOKEN: .word 0x20202020:3 # 2-word TOKEN & its TYPE
tokArray: .word 0x20202020:60 # initializing with blanks
inBuf: .space 80
space: .asciiz " "
st_prompt: .asciiz "Enter a new input line. \n"
st_error: .asciiz "An error has occurred. \n"
tableHead: .asciiz " TOKEN TYPE\n"
error: .asciiz "Double DeFinition Error"
hex: .asciiz "0x"
symTab: .word 0:40
tableHeader: .asciiz "Token Value Status \n"
dash: .asciiz "---------------------------------------------\n"
tempNewLine: .asciiz "\n"
.text
#######################################################################
#
#Main
#
#read an input line
#call scanner driver
#clear buffers
#
#Global Registers
#$t5 : index to inBuf in bytes
#$s0 : char type,T
#$s1 : next state Qx
#$s3 : index to the new char space in TOKEN
#$a3 : index to tokArray in 12 bytes per entry
#
######################################################################
li $s4,0x400 # LOC in $s4
li $t7,0 # symTab index
newline:
jal getline # get a new input string
li $t5,0 # $t5: index to inBuf
li $a3,0 # $a3: index to tokArray
#State table driver
la $s1,Q0 # initial state Q0
driver: lw $s2,0($s1) # get the action routine
jalr $v1,$s2 # execute the action
sll $s0,$s0,2 # compute byte offset of T
add $s1,$s1,$s0 # locate the next state
la $s1,($s1)
lw $s1,($s1) # next State in $s1
sra $s0,2 # reset $s0 for T
b driver # go to the next state
dump:
lb $t3,tokArray # if the first token is # exit
beq $t3,0x23,exit
li $s5,0 # index to tokArray[][]
nextTok:
lb $t3,tokArray+12($s5)
bne $t3,':',operator # check if next token is colon
lw $t4,tokArray+0($s5) # get current token
sw $t4,TOKEN
lw $t4,tokArray+4($s5)
sw $t4,TOKEN+4
li $s6,1 # DEFN = $s6 = 1
jal VARIABLE
addi $s5,$s5,24 # skip next token: �:�
operator:
addi $s5,12 # get next token index
li $s7,1 # $s7 = isComma = true
chkVar:
#lw $t3,tokArray + 8($s5)
#beq $t3,6,realDump #type is 6 �#� then dump
lb $t3,tokArray+0($s5)
beq $t3,'#',realDump
bne $s7,1,nextvar # not comma or type is not 2
lb $t3,tokArray+10($s5) # TESTEsstDSERS
subi $t3,$t3,0x30
bne $t3,2,nextvar
lw $t4,0 # DEFN = $s6 = 0
jal VARIABLE # call VARIABLE function
nextvar:
lb $t3,tokArray+0($s5) # check if token is �,�
beq $t3,0x2C,yes
bne $t3,no
yes:
li $s7,1
j after
no:
li $s7,0
j after
after:
addi $s5,12 # get next token index
b chkVar # check next token
realDump:
jal clearInBuf # clear input buffer
jal clearTokArray # clear token array
jal clearTok
jal printsymTab
addi $s4,$s4,4 # LOC +=4
b newline # ask for next input line
exit:
li $v0,10
syscall
VARIABLE:
sw $ra,saveReg # +0 = $ra
jal srchSymTab # symIndex = $t8
bge $t8,$zero,else
li $s0,0x4
or $t9,$s6 # newStatus = $t9
jal saveSymTab
b varEnd
else:
sw $t2,saveReg+4 # $t2 = oldStatus
lw $t2,symTab+12($t8)
and $t9,$t2,0x2
and $t2,0x1
sll $t2,1
or $t9,$t9,$t2
or $t9,$s6
sw $t9,symTab+12($t8)
lw $t2,saveReg+4
varEnd:
b realEnd
varRealEnd:
lw $ra,saveReg
jr $ra
saveSymTab:
sw $t9,symTab+12($t7)
sw $t2,saveReg+4
lw $t2,TOKEN
sw $t2,symTab+0($t7)
lw $t2,TOKEN+4
sw $t2,symTab+4($t7)
add $t8,$t7
addi $t7,$t7,16
lw $t2,saveReg+4
jr $ra
printsymTab:
sw $t2,saveReg+8
sw $t3,saveReg+12
sw $t4,saveReg+16
sw $t5,saveReg+20
li $t2,0
li $v0,4
la $a0,tableHeader # load header
syscall
la $a0,dash # load dashes
syscall
repeat:
beq $t2,ret
la $t3,symTab($t2)
lb $t4,symTab+8($t2)
li $t5,'\0'
sb $t5,symTab+8($t2)
move $a0,$t3
syscall
sb $t4,symTab+8($t2)
addi $t2,8
la $a0,space
syscall
li $v0,1
lw $a0,symTab($t2)
addi $t2,4
syscall
li $v0,space
syscall
la $a0,hex
syscall
li $v0,4
la $a0,tempNewLine
syscall
bc1f repeat
ret:
lw $t2,saveReg+8
lw $t3,saveReg+12
lw $t4,saveReg+16
lw $t5,saveReg+20
jr $ra
realEnd:
la $s0,symACTS # load address of symACTS to access the first line
sll $t9,2 # newStatus * 8
add $s0,$t9 # calculate the address of the correct symACT
sra $t9,2
jr $s0
symACTS:
b symACT0
b symACT1
b symACT2
b symACT3
b symACT4
b symACT5
symACT0:
lw $t1,symTab+8($t8)
sw $s4,symTab+8($t8)
b varRealEnd
symACT1:
lw $t1,symTab+8($t8)
b varRealEnd
symACT2:
lw $t1,symTab+8($t8)
b varRealEnd
symACT3:
la $a0,error
li $v0,4
syscall
li $t1,-1
b varRealEnd
symACT4:
sw $s4,symTab+8($t8)
li $t1,-1
b varRealEnd
symACT5:
sw $s4,0
b varRealEnd
srchSymTab:
sw $t2,saveReg+4
sw $t3,saveReg+8
sw $t4,saveReg+12
li $t2,0 # i index
li $t8,-1
startSearch:
bge $t2,srchEnd
lw $t3,symTab($t2)
bne $t3,$t4,update
lw $t3,TOKEN+4
lw $t4,symTab+4($t2)
bne $t3,update
add $t8,$t2
j srchEnd
update:
addi $t2,16
b startSearch
srchEnd:
lw $t2,saveReg+4
lw $t3,saveReg+8
lw $t4,saveReg+12
jr $ra
####################### STATE ACTION ROUTInes #####################
###################################################################
#
#ACT1:
#$t5 : Get next char
#T = char type
#
##############################################
ACT1:
lb $a0,inBuf($t5) # $a0: next char
jal lin_search # $s0: T (char type)
addi $t5,$t5,1 # $t5++
jr $v1
###############################################
#
#ACT2:
#save char to TOKEN for the first time
#save char type as Token type
#set remaining token space
#
##############################################
ACT2:
li $s3,0 # initialize index to TOKEN char
sb $a0,TOKEN($s3) # save 1st char to TOKEN
addi $t0,0x30 # T in ASCII
sb $t0,TOKEN+10($s3) # save T as Token type
li $t0,'\n'
sb $t0,TOKEN+11($s3) # NULL to terminate an entry
addi $s3,$s3,1
jr $v1
#############################################
#
#ACT3:
#collect char to TOKEN
#update remaining token space
#
#############################################
ACT3:
bgt $s3,7,lenError # TOKEN length error
sb $a0,TOKEN($s3) # save char to TOKEN
addi $s3,1 # $s3: index to TOKEN
jr $v1
lenError:
li $s0,7 # T=7 for token length error
jr $v1
#############################################
#
#ACT4:
#move TOKEN to tokArray
#
############################################
ACT4:
lw $t0,TOKEN($0) # get 1st word of TOKEN
sw $t0,tokArray($a3) # save 1st word to tokArray
lw $t0,TOKEN+4($0) # get 2nd word of TOKEN
sw $t0,tokArray+4($a3) # save 2nd word to tokArray
lw $t0,TOKEN+8($0) # get Token Type
sw $t0,tokArray+8($a3) # save Token Type to tokArray
addi $a3,$a3,12 # update index to tokArray
jal clearTok # clear 3-word TOKEN
jr $v1
############################################
#
#RETURN:
#End of the input string
#
############################################
RETURN:
sw $zero,tokArray($a3) # force NULL into tokArray
b dump # leave the state table
#############################################
#
#ERROR:
#Error statement and quit
#
############################################
ERROR:
la $a0,st_error # print error occurrence
li $v0,4
syscall
b dump
############################### BOOK-KEEPING FUNCTIONS #########################
#############################################
#
#clearTok:
#clear 3 - word TOKEN after copying it to tokArray
#
#############################################
clearTok:
li $t1,0x20202020
sw $t1,TOKEN($0)
sw $t1,TOKEN+4($0)
sw $t1,TOKEN+8($0)
jr $ra
#############################################
#
#printline:
#Echo print input string
#
#############################################
printline:
la $a0,inBuf # input Buffer address
li $v0,4
syscall
jr $ra
#############################################
#
#printTokArray:
#print Token array header
#print each token entry
#
#############################################
printTokArray:
la $a0,tableHead # table heading
li $v0,4
syscall
la $a0,tokArray # print tokArray
li $v0,4
syscall
jr $ra
############################################
#
#clearInBuf:
#clear inBox
#
############################################
clearInBuf:
li $t0,0
loopInB:
bge $t0,80,doneInB
sw $zero,inBuf($t0) # clear inBuf to 0x0
addi $t0,$t0,4
b loopInB
doneInB:
jr $ra
###########################################
#
#clearTokArray:
#clear Token Array
#
###########################################
clearTokArray:
li $t0,0
li $t1,0x20202020 # intialized with blanks
loopCTok:
bge $t0,doneCTok
sw $t1,tokArray($t0) # clear
sw $t1,tokArray+4($t0) # 3-word entry
sw $t1,tokArray+8($t0) # in tokArray
addi $t0,12
b loopCTok
doneCTok:
jr $ra
###################################################################
#
#getline:
#get input string into inBox
#
###################################################################
getline:
la $a0,st_prompt # Prompt to enter a new line
li $v0,inBuf # read a new line
li $a1,80
li $v0,8
syscall
jr $ra
##################################################################
#
#lin_search:
#Linear search of Tabchar
#
#$a0 : char key
#$s0 : char type,T
#
#################################################################
lin_search:
li $t0,0 # index to Tabchar
li $s0,7 # return value,type T
loopSrch:
lb $t1,Tabchar($t0)
beq $t1,0x7F,charFail
beq $t1,$a0,charFound
addi $t0,8
b loopSrch
charFound:
lw $s0,Tabchar+4($t0) # return char type
charFail:
jr $ra
.data
STAB:
Q0: .word ACT1
.word Q1 # T1
.word Q1 # T2
.word Q1 # T3
.word Q1 # T4
.word Q1 # T5
.word Q1 # T6
.word Q11 # T7
Q1: .word ACT2
.word Q2 # T1
.word Q5 # T2
.word Q3 # T3
.word Q3 # T4
.word Q0 # T5
.word Q4 # T6
.word Q11 # T7
Q2: .word ACT1
.word Q6 # T1
.word Q7 # T2
.word Q7 # T3
.word Q7 # T4
.word Q7 # T5
.word Q7 # T6
.word Q11 # T7
Q3: .word ACT4
.word Q0 # T1
.word Q0 # T2
.word Q0 # T3
.word Q0 # T4
.word Q0 # T5
.word Q0 # T6
.word Q11 # T7
Q4: .word ACT4
.word Q10 # T1
.word Q10 # T2
.word Q10 # T3
.word Q10 # T4
.word Q10 # T5
.word Q10 # T6
.word Q11 # T7
Q5: .word ACT1
.word Q8 # T1
.word Q8 # T2
.word Q9 # T3
.word Q9 # T4
.word Q9 # T5
.word Q9 # T6
.word Q11 # T7
Q6: .word ACT3
.word Q2 # T1
.word Q2 # T2
.word Q2 # T3
.word Q2 # T4
.word Q2 # T5
.word Q2 # T6
.word Q11 # T7
Q7: .word ACT4
.word Q1 # T1
.word Q1 # T2
.word Q1 # T3
.word Q1 # T4
.word Q1 # T5
.word Q1 # T6
.word Q11 # T7
Q8: .word ACT3
.word Q5 # T1
.word Q5 # T2
.word Q5 # T3
.word Q5 # T4
.word Q5 # T5
.word Q5 # T6
.word Q11 # T7
Q9: .word ACT4
.word Q1 # T1
.word Q1 # T2
.word Q1 # T3
.word Q1 # T4
.word Q1 # T5
.word Q1 # T6
.word Q11 # T7
Q10: .word RETURN
.word Q10 # T1
.word Q10 # T2
.word Q10 # T3
.word Q10 # T4
.word Q10 # T5
.word Q10 # T6
.word Q11 # T7
Q11: .word ERROR
.word Q4 # T1
.word Q4 # T2
.word Q4 # T3
.word Q4 # T4
.word Q4 # T5
.word Q4 # T6
.word Q4 # T7
Tabchar:
.word ' ',5
.word '#',6
.word '$',4
.word '(',4
.word ')',4
.word '*',3
.word '+',3
.word ',',4
.word '-',3
.word '.',4
.word '/',3
.word '0',1
.word '1',1
.word '2',1
.word '3',1
.word '4',1
.word '5',1
.word '6',1
.word '7',1
.word '8',1
.word '9',1
.word ':',4
.word 'A',2
.word 'B',2
.word 'C',2
.word 'D',2
.word 'E',2
.word 'F',2
.word 'G',2
.word 'H',2
.word 'I',2
.word 'J',2
.word 'K',2
.word 'L',2
.word 'M',2
.word 'N',2
.word 'O',2
.word 'P',2
.word 'Q',2
.word 'R',2
.word 'S',2
.word 'T',2
.word 'U',2
.word 'V',2
.word 'W',2
.word 'X',2
.word 'Y',2
.word 'Z',2
.word 'a',2
.word 'b',2
.word 'c',2
.word 'd',2
.word 'e',2
.word 'f',2
.word 'g',2
.word 'h',2
.word 'i',2
.word 'j',2
.word 'k',2
.word 'l',2
.word 'm',2
.word 'n',2
.word 'o',2
.word 'p',2
.word 'q',2
.word 'r',2
.word 's',2
.word 't',2
.word 'u',2
.word 'v',2
.word 'w',2
.word 'x',2
.word 'y',2
.word 'z',2
.word 0x7F,0
解决方法
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