MIPS十六进制转十进制程序调试求助：输出异常负数与最大值错误

我正在编写一款MIPS十六进制转十进制转换器，程序需从命令行接收最多8个以0x开头、4字节长且以空字符结尾的十六进制字符串参数，$s1存储参数数量，$s0指向参数列表起始位置。

使用测试参数0x1A、0xF1、0x0B3运行时，程序输出出现异常：Integer values显示为-2121474836290，Maximum value显示为0，而正确结果应为26、241、179，最大值为241。

现附上程序代码，请求协助调试解决问题：

.data
buffer: .space 32
args: .asciiz "\nProgram arguments:\n"
space: .asciiz " "
d_rep: .asciiz "\n\nInteger values:\n"
newLine: .asciiz "\n"
maxVal: .asciiz "Maximum value:\n"
.text
main:
add $t9, $zero, $zero # t9 will be max value
add $s1, $a0, $0 # store number of program arguments
add $s2, $a1, $0 # store address of where program arguments are
addi $s0, $0, 0 # use s0 as index for looping
addi $s7, $zero, 0 # used as index for print loop
add $s6, $s1, $0 # store numArgs for printloop
add $s5, $s2, $0 # store address for printloop
addi $t5, $zero, 16
addi $t6, $zero, 0
la $a0, args # load and print "Program arguments" string
li $v0, 4 # print syscall
printloop:
beq $s7, $s6, printInt # only print as many times as there are args
lw $a0, 0($s5) # get the first word
li $v0, 4 # print syscall
la $a0, space # print a space between words
li $v0, 4 # print syscall
addi $s5, $s5, 4 # increment to next word
addi $s7, $s7, 1 # increment printloop counter
j printloop # loop again if there are more args
printInt:
la $a0, d_rep # print "Decimal values:"
li $v0, 4 # print syscall
while:
beq $s0, $s1, done # while $s0 <= numArgs
lb $t1, 2($s2) # load s2[2] into
addu $t2, $zero, $t1 # make a copy so we dont lose place
subiu $sp, $sp, 4
convert:
beqz $t2, postConv # while t2 != null
blt $t2, 65, convNumber # if less than value of A then got a num
subiu $t3, $t2, 0x37 # -55 for uppercase letter
sll $t3, $t3, 4 # sll by 4 is same as mult by 16
sw $t3, ($sp) # store word to do some addition
addiu $t2, $t2, 1 # increment t2
subiu $sp, $sp, 4 # increment sp
j convert # go back to convert
convNumber:
addu $t3, $zero, $t2 # put t2 into t3 for to do some math
subiu $t3, $t3, 0x30 # -48 for number
sll $t3, $t3, 4 # sll by 4 is same as mult by 16
sw $t3, ($sp)
addiu $t2, $t2, 1 # increment t1
addiu $sp, $sp, 4 # increment sp
j convert # jump back to convert
postConv:
addi $sp, $sp, 4 # load the second value
lw $s4, ($sp) # load the first value
addi $sp, $sp, 4 #
sll $s4, $s4, 4
lw $s3 ($sp)
addu $s3, $s3, $s4 # add em up for converted decimal
move $a0, $s3 # move to a0 so they pint
li $v0, 1 # print syscall
addiu $s0, $s0, 1 # increment loop counter
addiu $s2, $s2, 4 # increment to next word
ble $t9, $t6, newMax # check for a new max value
j while # jump back to loop
newMax:
addu $t9, $zero, $t6 # got a new max so save it
j while
done:
la, $a0, newLine
li $v0, 4
syscall
la, $a0, newLine
li $v0, 4
syscall
la, $a0, maxVal
li $v0, 4
syscall
move $a0, $t9
li $v0, 1
syscall
la, $a0, newLine
li $v0, 4
syscall
li $v0, 10 # end program
syscall

内容的提问来源于stack exchange，提问作者Jake