Advanced Assembly Programming - The HCS12/9S12: An Introduction to Software and Hardware Interfacing - page 179

Otherwise, a value of zero is returned. The following instruction sequence illustrates the use
of this function:
isxdigit equ $EE92

…

c_buf ds.b 20 ; buffer that holds data to be validated

…

clra ; clear accumulator A

ldab c_buf ; get one character

jsr [isxdigit,PCR]

…
int toupper(int c);
Pointer address: $EE94
If c is a lowercase character, toupper() will return the corresponding uppercase letter. If the
character is in uppercase, it simply returns c. The following instruction utilizes this function to
convert a character contained in B to uppercase:
toupper equ $EE94

…

c_buf ds.b 20 ; buffer that contains string to be converted to

… ; uppercase

ldab c_buf ; get one character to convert

clra

jsr [toupper,PCR]

…
int isalpha(int c);
Pointer address: $EE96
This function tests the character passed in c for membership in the character set [a..z, A..Z].
If the character c is in this set, the function returns a nonzero value. Otherwise, it returns a
zero. This function would also be useful for validating an input string. The following instruc-
tion sequence illustrates the use of this function:
isalpha equ $EE96

…

c_buf ds.b 20

…

ldab c_buf

clra

jsr [isalpha,PCR] ; check whether the character in B is alphabetic

…
unsigned int strlen(const char *cs);
Pointer address: $EE98
The strlen() function returns the length of the string pointed to by cs . The following instruc-
tion sequence counts the number of characters contained in the string pointed to by cs:
strlen equ $ EE98

…

cs db “…..”

…