How do I modify my code to compare the user input against "QUIT" and have it exit the loop if they don't match?

Question

When I run my program, it is supposed to go through the rest of my code when I type anything but QUIT, but when I type anything, it just HALTS my program.

This question is the same project that I'm working on, but at a different stage-text

I have tried modifying my code as to the order it executes, but it doesn't help. I have gone through the debugger, but can't identify the exact problem.

Here is my code for this specfic loop, for reference:

; String compare function
    STRING_COMPARE_QUIT AND R0, R0, #0 ; Initialize result to 0
        ; R1 points to 'QUIT', R2 to INPUT_BUFFER
        ; R3/R4 are characters from the strings
        ; R5 is a comparison flag, R6 for lowercase checking
        ; R6 is the lowercase mask
        CASE_INSENSITIVE_COMPARE_QUIT
            LEA   R1, QUIT           ; Point to the string "QUIT"
            LD    R2, INPUT_BUFFER   ; Point to the input buffer
            AND   R5, R5, #0         ; Clear the comparison flag

            CHECK_LOOP_QUIT
                LDR   R3, R1, #0         ; Load character from "QUIT"
                LDR   R4, R2, #0         ; Load character from input buffer

                ; Check if R3 is lowercase and convert it to uppercase if it is
                LD    R6, MASK     ; Load the lowercase mask value into R6
                AND   R6, R3, R6         ; Mask off bits with R6 to check if it's a lowercase letter
                BRz   NOT_LOWERCASE_1_QUIT    ; Zero flag means it's not a lowercase letter
                ADD   R3, R3, #0         ; Make sure condition codes are set based on R3
                BRn   NOT_LOWERCASE_1_QUIT    ; Negative flag means it's not a lowercase letter (ASCII < 'a')
                BRzp  CASE_CHECK_R3_QUIT      ; Zero or positive means we have a lowercase letter
                NOT_LOWERCASE_1_QUIT
                BRnzp SKIP_CONVERSION_1_QUIT  ; Skip conversion if not lowercase
                
                CASE_CHECK_R3_QUIT
                    LD    R6, MASK           ; Load the value 32 into R6 from memory
                    AND   R6, R3, R6         ; Apply mask with R6 to check if R3's character is lowercase
                    BRz   CONVERT_R3_QUIT         ; If zero, convert this lowercase to uppercase
                    ; This label is no longer needed since BRnzp is unconditional here and
                    ; we don't have any instructions in between
                    SKIP_CONVERSION_1_QUIT    ; This line should be removed eventually, unless you have more code to add here.
                    BRnzp NEXT_INSTRUCTION_QUIT   ; Always jump to the next instructionstruction if no conversion needed
                    CONVERT_R3_QUIT
                        LD   R6, TO_UPPERCASE  ; Load the value 32 into R6
                        NOT  R3, R3            ; Invert R3 to prepare for addition
                        ADD  R3, R3, #1        ; Add 1 to complete 2's complement negation
                        ADD  R3, R3, R6        ; Add R6 (which is 32) to complete the subtraction, effectively converting lowercase to uppercase
                    NEXT_INSTRUCTION_QUIT
                    ; Check if R4 is lowercase and convert it to uppercase if it is
                    LD    R6, MASK ;
                    AND   R6, R4, R6     ; Mask off bits to check if it's a lowercase letter
                    BRz   NOT_LOWERCASE_2_QUIT    ; Zero flag means it's not a lowercase letter
                    ADD   R4, R4, #0         ; Make sure condition codes are set based on R4
                    BRn   NOT_LOWERCASE_2_QUIT    ; Negative flag means it's not a lowercase letter (ASCII < 'a')
                    BRzp  CASE_CHECK_R4      ; Zero or positive means we have a lowercase letter
                    NOT_LOWERCASE_2_QUIT
                    BRnzp SKIP_CONVERSION_2_QUIT  ; Skip conversion if not lowercase
                CASE_CHECK_R4_QUIT
                    LD    R6, MASK
                    AND   R6, R4, R6
                    BRz CONVERT_R4_QUIT
                    SKIP_CONVERSION_2_QUIT
                    BRnzp NEXT_INSTRUCTION_FOR_R4_QUIT
                    CONVERT_R4_QUIT
                    LD   R6, TO_UPPERCASE
                    NOT R4, R4
                    ADD R3, R3, #1
                    ADD   R4, R4, R6      ; Convert lowercase to uppercase by adding binary 0010000
                    ; Continue on with the processing of R4
                    NEXT_INSTRUCTION_FOR_R4_QUIT
                ADD R6, R3, #0  ; Update flags based on R3 value
                BRz   CHECK_QUIT_END   ; If R3 is NULL, go check input buffer end
                ADD   R6, R4, #0         ; Update flags based on R4 value
                BRz   STRINGS_NOT_EQUAL_QUIT ; If R4 is NULL here, it's a mismatch
                ; No NULL is encountered, so compare the characters
                CHAR_EQUAL_QUIT
                    ADD   R1, R1, #1         ; Increment to the next character of "QUIT"
                    ADD   R2, R2, #1         ; Increment to the next character of the input buffer
                    BRnzp CHECK_LOOP         ; Continue the loop
                CONTINUE_COMPARE_QUIT
                    ADD   R1, R1, #1       ; Move to the next character in "QUIT"
                    ADD   R2, R2, #1       ; Move to the next character in input buffer
                    BRnzp CHECK_LOOP_QUIT       ; Loop back
                CHECK_QUIT_END
                    ADD   R6, R4, #0       ; Copy R4 to check if input also ends
                    BRz   STRINGS_ARE_EQUAL_QUIT  ; If R4 is NULL, both strings end here, thus are equal
                    BRnzp STRINGS_NOT_EQUAL_QUIT  ; If R4 is not NULL, mismatch
                STRINGS_NOT_EQUAL_QUIT
                    BRnzp STRING_COMPARE_QUIT_EXIT

                STRINGS_ARE_EQUAL_QUIT
                    ; Set flag for "equal", Input matches "QUIT" (case insensitive)
                    AND   R5, R5, #0       ; Clear R5
                    ADD   R5, R5, #1       ; Set R5 to indicate strings are equal
                    BRzp EXIT
        STRING_COMPARE_QUIT_EXIT