Skip to navigation


[6502 Second Processor version]

Name: VOWEL [Show more] Type: Subroutine Category: Text Summary: Test whether a character is a vowel
Context: See this subroutine in context in the source code References: This subroutine is called as follows: * MT17 calls VOWEL

Arguments: A The character to be tested
Returns: C flag The C flag is set if the character is a vowel, otherwise it is clear
.VOWEL ORA #%00100000 \ Set bit 5 of the character to make it lower case CMP #'a' \ If the letter is a vowel, jump to VRTS to return from BEQ VRTS \ the subroutine with the C flag set (as the CMP will CMP #'e' \ set the C flag if the comparison is equal) BEQ VRTS CMP #'i' BEQ VRTS CMP #'o' BEQ VRTS CMP #'u' BEQ VRTS CLC \ The character is not a vowel, so clear the C flag .VRTS RTS \ Return from the subroutine