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copied!<p>Second Edit: </p> <p>Okay, this now works correctly for your example check code but I cannot guarantee that there are not hidden bugs or any mistakes. It will print either correct or incorrect for the control code given the 16 character fiscal code. </p> <p>It is very repetitive as I could not find very many patterns in the odd positions that and I did not want to do anything to complex. I made it fairly simple and commented it thoroughly.</p> <p>Any further questions or comments don't hesitate to ask.</p> <pre><code># Italian Fiscal Code Calculation in MIPS .data ArraySpace: .space 18 lookupTableOdd: .ascii "10579" msgOk: .asciiz "\nCorrect control code!" msgFail: .asciiz "\nIncorrect control code!" .text main: li $v0, 8 # read string to store into ArraySpace la $a0, ArraySpace # load address of fiscal value attempt li $a1, 18 # length 16 + '\n' syscall # tell system to read string addi $t2, $a1, -2 # length of string li $t3, 0 # i = 0 (our string iterator) jal loop # actually loop through input string li $t9, 26 # load 26 for divison div $t5, $t9 # divide total in $t5 by 26 mflo $t4 # move result into $t4 jal controlCode # calculate control code move $t5, $t4 # move our calculated check code to $t5 jal checkCode # check control code li $v0, 10 # exit code syscall # terminate nicely checkCode: addi $t2, $t2, -1 # backup to last index in string lbu $t4, ArraySpace($t2) # load the control code of the input string (last index) blt $t4, 65, endLoop # should not get something below 65 bgt $t4, 122, endLoop # not valid character above 122 addi $t4, $t4, -65 # get alphabet value 0-25 bge $t4, 32, case_convert_ch # if a-z we have to sub 32 beq $t5, $t4, checkOk # checkcode is equal to calculated code j checkFail # else fail checkFail: li $v0, 4 # print fail la $a0, msgFail # load failed code message syscall # print it j endLoop case_convert_ch: addi $t4, $t4, -32 # make lowercase 'A'-'a'=-32 beq $t4, $t5, checkOk # if equal print ok j checkFail # else fail controlCode: bgt $t4, 4, checkDigit # >4 is two digit value lbu $t4, lookupTableOdd($t4) # fetch corresponding value addi $t4, $t4, -48 # get digit value j endLoop checkDigit: # this is for 5 to 9 in odd positions sub $t4, $t4, 5 # value - 5 mul $t9, $t4, 2 # multiply this by 2 li $t4, 13 # the base is 13 add $t4, $t4, $t9 # 13 + factor of 2 j endLoop case_convert_cc: addi $t4, $t4, -32 # uppercase: 'A'-'a'=-32 bgt $t4, 4, oddDigit # >4 is two digit value lbu $t4, lookupTableOdd($t4) # fetch corresponding value addi $t4, $t4, -48 # get digit value j endLoop checkOk: li $v0, 4 # print string la $a0, msgOk # load ok message syscall # print it j endLoop loop: bge $t3, $t2, endLoop # if greater than length of string end andi $t8, $t3, 1 # logical AND result into $t2 (even = 0, odd = 1) beq $t8, $zero, evenLoop # on even positions goto evenLoop j oddLoop # on odd positions goto oddLoop evenLoop: lbu $t4, ArraySpace($t3) # load the i index of the input string blt $t4, 48, endLoop # should not get something below 48 bgt $t4, 57, evenCharLoop # not a digit addi $t4, $t4, -48 # get digit value j continueLoop oddLoop: lbu $t4, ArraySpace($t3) # load the i index of the input string blt $t4, 48, endLoop # should not get something below 48 bgt $t4, 57, oddCharLoop # not a digit addi $t4, $t4, -48 # get digit value bgt $t4, 4, oddDigit # >4 is two digit value lbu $t0, lookupTableOdd($t4) # fetch corresponding value addi $t4, $t0, -48 # get digit value j continueLoop oddDigit: # this is for 5 to 9 in odd positions sub $t4, $t4, 5 # value - 5 mul $t9, $t4, 2 # multiply this by 2 li $t4, 13 # the base is 13 add $t4, $t4, $t9 # 13 + factor of 2 j continueLoop evenCharLoop: blt $t4, 65, endLoop # should not get something below 65 bgt $t4, 122, endLoop # not valid char addi $t4, $t4, -65 # get alphabet value bge $t4, 32, case_convert_even # if a-z we have to sub 32 add $t5, $t5, $t4 # add the alpha value A-Z to our sum add $t3, $t3, 1 # i++ j loop oddCharLoop: blt $t4, 65, endLoop # should not get something below 65 bgt $t4, 122, endLoop # not valid char addi $t4, $t4, -65 # get alphabet value bge $t4, 32, case_convert_odd # if a-z we have to sub 32 j oddProcess ## this should probably be done better but I did not find many patterns ## oddDigitCheck: ble $t4, 9, oddDigit # F>=x<=J is two digit value of factor 2 sub $t4, $t4, 10 # >=K blt $t4, 2, KL # 0-K 1-L blt $t4, 4, MN # 2-M 3-N beq $t4, 4, O # 4-O blt $t4, 7, PQ # 5-P 6-Q beq $t4, 7, R # 7-R blt $t4, 11, STU # 8-S 9-T 10-U beq $t4, 11, V # 11-V beq $t4, 12, W # 12-W blt $t4, 16, XYZ # 13-X 14-Y 15-Z oddProcess: bgt $t4, 4, oddDigitCheck # >E could be two digit value lbu $t0, lookupTableOdd($t4) # fetch corresponding value (A-E) addi $t0, $t0, -48 # get digit value add $t5, $t5, $t0 # add the digit to our sum add $t3, $t3, 1 # i++ j loop case_convert_even: addi $t4, $t4, -32 # to uppercase: 'A'-'a'=-32 j continueLoop case_convert_odd: addi $t4, $t4, -32 # to uppercase: 'A'-'a'=-32 j oddProcess endLoop: jr $ra # jump and return XYZ: sub $t4, $t4, 13 # X or Y or Z li $t9, 25 # base is 25 sub $t4, $t9, $t4 # 25 - (0,1,2) j continueLoop W: li $t4, 22 # W = 22 j continueLoop V: li $t4, 10 # V = 10 j continueLoop STU: sub $t4, $t4, 8 # S or T or U mul $t9, $t4, 2 # mult by 2 li $t4, 12 # base of 12 add $t4, $t4, $t9 # add factor j continueLoop R: li $t4, 8 # R = 8 j continueLoop PQ: sub $t4, $t4, 5 # P or Q mul $t9, $t4, 3 # mult by 3 li $t4, 3 # base of 3 add $t4, $t4, $t9 # add factor j continueLoop O: li $t4, 11 # O = 11 j continueLoop MN: sub $t4, $t4, 2 # M or N mul $t9, $t4, 2 # mult by 2 li $t4, 18 # base of 18 add $t4, $t4, $t9 # add factor j continueLoop KL: mul $t9, $t4, 2 # mult by 2 li $t4, 2 # base of 2 add $t4, $t4, $t9 # add factor j continueLoop continueLoop: add $t5, $t5, $t4 # add the digit to our sum add $t3, $t3, 1 # i++ j loop </code></pre>

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