;; This example shows how to perform a directory of a disc
;; and extract the filenames. 
;;
;; This code is public domain and can freely be used in your
;; own programs.
;;
;; Written by Kevin Thacker. 2002


;;------------------------------------------------------------------

;; firmware function to catalog a disc or cassette
cas_catalog == 0xbc9b
;; firmware function to disable text output
txt_vdu_enable == 0xbb54
;; firmware function to enable text output
txt_vdu_disable == 0xbb57
;; firmware function to find a RSX 
kl_find_command == 0xbcd4

		.globl __readdir
		.area _CODE

;; void _readdir(void*)
;; Input: pointer to buffer in HL
__readdir::

	; The AMSDOS call corrupts IX, which must be saved for SDCC code to work
	PUSH IX

	; The parameter is passed in HL but we need it in DE
	EX DE,HL

;; disable disc messages. Error messages will not be displayed.
ld a,#0xff
rst 0x018						;; KL FAR CALL
.dw bios_set_message

;; disable text output
call txt_vdu_disable

	; Make sure to return an empty buffer if getting the catalog fails
	xor a
	ld (DE),a

;; do catalog
	call cas_catalog

;; enable text output
call txt_vdu_enable

;; enable disc messages. Error messages will be displayed
xor a
rst 0x018						;; KL FAR CALL
.dw bios_set_message

	POP IX
ret


;;------------------------------------------------------------------

;; this is initialised when the "BIOS SET MESSAGE" RSX has been found.
bios_set_message:
.dw 0xc033                    ;; address of function
.db 7                    ;; "rom select" for function