This is a question on homework from CS2400 MSU Denver
Hello,
I have a program that reads keys from the user until they have either entered a non HEX character or entered a max of 8 HEX characters. As keys are entered I maintain a sum of hex values being entered by the user by multiplying the sum register by 16 and adding the new hex value.
This part is all fine and dandy, no help needed. I am having trouble taking this final result, in HEX, and converting it to DEC. I know I need to divide by 10 only I don't know how I can accomplish this.
Please help me determine how to divide by 10 and save the quotient and remainder. Thanks.
AREA HW6, CODE
ENTRY
Divsor EQU 10
MAIN
MOV R1, #0 ; Clear register to be used as symbols received counter
MOV R2, #0 ; Clear register to be used as temp result
LDR R4, =DecStr ; Load address of DecStr
LDR R5, =TwosComp ; Load address of TwosComp
LDR R6, =RvsDecStr
BL READ_CHARS ; Read characters from the keyboard
BL TO_DECIMAL ; Is R2 negative ?
SWI 0x11
READ_CHARS
CMP R1, #8 ; Check if necessary to read another key
BEQ DONE_READ_CHAR ; User has entered 8 hex symbols
SWI 4 ; [R0] <--- Key from keyboard (ASCII)
CMP R0, #'0' ; Verify digit is valid
BLO DONE_READ_CHARS
CMP R0, #'9' ; Verify digit is valid
BHI CHECK_HEX
SUB R0, R0, #'0' ; Obtain Hex equivalent of ASCII char 0-9
B STORE_INPUT
CHECK_HEX
CMP R0, #'A'
BLO DONE_READ_CHARS ; Invalid Hex symbol
CMP R0, #'F'
BHI DONE_READ_CHARS ; Invalid Hex symbol
SUB R0, R0, #'A'
ADD R0, R0, #0xA ; Adding ten to receive Hex equivalent of ASCII A-F
STORE_INPUT
MOV R3, R2, LSL#4 ; *16
ADD R2, R3, R0 ; Add valid Hex symbol to temp result
ADD R1, R1, #1 ; Increase symbol's recieved counter
B READ_CHARS ; Get next key
DONE_READ_CHARS
MOV PC, LR ; Return to BL READ_CHARS ( MAIN )
TO_DECIMAL
TST R2, #2, 2
BEQ POSITIVE
STRB #'-', [R4], #1 ; Store - as first byte in DecStr
MVN R2, R2 ; [R2] <- 1's complement of R2
ADD R2, R2, #1 ; [R2] <- 2's complement of R2
POSITVE
STR R2, [R5] ; Store all entered hex values in memory at TwosComp
LDR R7, [R5] ; Initial quotient
udiv10
LDRB R7, [R5], #1 ; Load a byte of TwosComp
CMP R7, #0
BEQ DONE_TO_DECIMAL
DONE_TO_DECIMAL
MOV PC, LR
AREA data1, DATA
TwosComp
DCD 0
DecStr % 12
RvsDecStr
% 11
ALLIGN
END
