Documentation for the strings module

(This documentation was generated automatically from the file strings.asm by asmdoc on Nov 22, 2000.)
This module contains a collection of string routines. The routines are similar to some of the those in the Standard C strings library.

This module conforms to the conventions described in Assembly Language Coding Standards.

The subroutines in this module cannot be called from a high-level language (like C); they can only be invoked from assembler.

To use any of these routines, link strings.o.

These routines have not been tested extensively. Use at your own risk!


Version: 1.0
Author: Ken Clowes


           
Summary
strlen            Determines the length of a null-terminated string.
strcpy            Copies a null-terminated string.
strrev            Reverses a string in place.

           
Details

strlen

Determines the length of a null-terminated string. If the string is less than 256 characters in length, the correct length is returned in Accumulator B and the Carry bit in the Condition Code register is cleared. Otherwise, the C bit is set.


Since: 1.0

Parameters:
Register X -- the starting address of the string
Returns:
AccB -- the length of the string (if less than 256 characters).
CC -- Carry bit Set if length > 255; else Cleared
Side effects:
none
Examples:
The following shows an elementary use of strlen. 
 msg: .asciz "Hello world";
    ....
    ldx #msg
    jsr strlen ;on return B <-- 11; Carry is clear
    bcs tooBig

strcpy

Copies a null-terminated string. The string to be copied is passed in IX and the address of the destination is IY.

Parameters:
IX starting address of source string
IY starting address of destination string
Returns:
nothing
Side effects:
none

strrev

Reverses a string in place. The IX register points to a null-terminated string. The same string is reversed in place (not copied). If the string is more than 255 characters in length, the results are unpredictable.

Examples:
The string "abcd" will be reversed to the string "dcba".

Parameters:
IX--starting address of the string to be reversed
Returns:
nothing
Side effects:
Condition Code register (CC) modified.
Since: 1.0
Author: Ken Clowes