work towards directory filtering in CBDOS

src/dos_m65/dev_sdcard/dev_sd_cmd_open.s

@@ -19,11 +19,37 @@ dev_sd_cmd_OPEN_EOI:
 
 	lda SD_CMDFN_BUF
 	cmp #'$'
-	+beq fs_hvsr_read_dir_open
+	beq dev_sd_cmd_OPEN_dir
 
 	; XXX implement for file names
 
 	jmp dos_EXIT_SEC
 
 
+dev_sd_cmd_OPEN_dir:
 
+	; XXX this should be moved to common part
+
+	; Erase filter pattern for the directory
+
+	ldy #$0F
+	lda #$A0
+@lp1:
+	sta PAR_FPATTERN, y
+	dey
+	bpl @lp1
+
+	; Copy the filter from command
+
+	ldy #$00
+@lp2:
+	lda SD_MODE, y
+	beq @lp2_end
+	sta PAR_FPATTERN, y
+	iny
+	cpy #$10
+	bne @lp2_end
+
+@lp2_end:
+
+	jmp fs_hvsr_read_dir_open

src/dos_m65/dev_sdcard/fs_hvsr_read_dir.s

@@ -60,6 +60,12 @@ fs_hvsr_read_dir:
 
 	+bcs fs_hvsr_read_dir_blocksfree
 
+	; Check if file name matches the filter
+
+	; XXX debug this
+	; jsr util_dir_filter
+	; bne fs_hvsr_read_dir               ; if does not match, try the next entry
+
 	; Otherwise, convert the file length from bytes to blocks to display
 
 	jsr util_dir_filesize_bytes

src/dos_m65/utils/util_dir_filter.s

@@ -0,0 +1,28 @@
+
+; Check if file name matches the filter (if so - Zero flag set)
+
+
+util_dir_filter:
+
+	lda PAR_FPATTERN
+	cmp #$A0
+	beq @done                          ; branch if no filter
+
+	ldy #$00
+
+@lp1:
+
+	lda PAR_FPATTERN, y
+	cmp #'*'
+	beq @done                          ; branch on wildcard
+
+	cmp PAR_FNAME, y
+	bne @done                          ; branch if does not match
+
+	iny
+	cpy #$10
+	bne @lp1                           ; next iteration if maximum length not reached
+
+@done:
+
+	rts