View source for 83Plus:Software:usb8x/Asm Interface/MSD/DOS fileWrite

== Synopsis ==
'''Name:''' DOS_fileWrite

'''Minimum usb8x version:''' 0.10

Writes bytes to a file and grows it if necessary.

=== Inputs ===
* HL points to file handle of an opened file
* DE points to a buffer of bytes to write
* BC is the number of bytes to write

=== Outputs ===
* BC is the number of bytes actually written
* C set if problems

=== Destroys ===
* AF, BC, DE, HL

== Notes ==
Example code to write "This is a test" to "readme.txt" in the root directory:
<code>
 ld hl,sFilename
 ld de,file_handle
 U_CALL DOS_openFile
 ;HL points to file handle
 ld de,sWrite
 ld bc,14
 U_CALL DOS_fileWrite
 ...
 sFilename: DB "/readme.txt",0
 sWrite: DB "This is a test"
</code>
If you are writing an application, you must copy the strings you use to RAM first, or else usb8x will not be able to see them.

== See Also ==
* [[../DOS_fileRead|DOS_fileRead]] - Read bytes from a file at current seek pointer
* [[../DOS_fileSeek|DOS_fileSeek]] - Set seek pointer in file handle