some work towards PRG file loading via CBDOS

src/dos_m65/dev_sdcard/dev_sd_cmd_open.s

@@ -15,22 +15,7 @@ dev_sd_cmd_OPEN_EOI:
 
 	; XXX this dispatcher is temporary
 
-	; XXX add support for second card
-
-	lda SD_CMDFN_BUF
-	cmp #'$'
-	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
+	; Erase filter pattern     XXX this should be moved to common part
 
 	ldy #$0F
 	lda #$A0
@@ -39,18 +24,47 @@ dev_sd_cmd_OPEN_dir:
 	dey
 	bpl @lp1
 
-	; Copy the filter from command
+	; XXX add support for second card
+
+	lda SD_CMDFN_BUF
+	cmp #'$'
+	beq dev_sd_cmd_OPEN_dir
+
+	; FALLTROUGH
+
+dev_sd_cmd_OPEN_file:
+
+	; Copy the filter from command     XXX this should be moved to common part and deduplicated with directory opening
 
 	ldy #$00
-@lp2:
-	lda SD_CMDFN_BUF+1, y
+@lp1:
+	lda SD_CMDFN_BUF, y
 	cmp #$A0
-	beq @lp2_end
+	beq @lp1_end
 	sta PAR_FPATTERN, y
 	iny
 	cpy #$10
-	bne @lp2
+	bne @lp1
 
-@lp2_end:
+@lp1_end:
+
+	jmp fs_hvsr_read_file_open
+
+
+dev_sd_cmd_OPEN_dir:
+
+	; Copy the filter from command     XXX this should be moved to common part and deduplicated with file opening
+
+	ldy #$00
+@lp1:
+	lda SD_CMDFN_BUF+1, y
+	cmp #$A0
+	beq @lp1_end
+	sta PAR_FPATTERN, y
+	iny
+	cpy #$10
+	bne @lp1
+
+@lp1_end:
 
 	jmp fs_hvsr_read_dir_open

src/dos_m65/dev_sdcard/fs_hvsr_open_file.s

@@ -1,12 +0,0 @@
-
-;
-; Hypervisor virtual filesystem - opening the file
-;
-
-
-fs_hvsr_read_file_open:
-
-	; XXX provide implementation
-
-	sec
-	rts

src/dos_m65/dev_sdcard/fs_hvsr_read_dir.s

@@ -4,9 +4,6 @@
 ;
 
 
-; XXX optimize the flow; we do not need 256-byte SD_DIRENT buffer, directory entries can be constructed directly
-
-
 fs_hvsr_read_dir_open:
 
 	; Open the directory

src/dos_m65/dev_sdcard/fs_hvsr_read_file.s

@@ -0,0 +1,72 @@
+
+;
+; Hypervisor virtual filesystem - opening the file
+;
+
+
+fs_hvsr_read_file_open:
+
+	; Open the directory
+
+	lda #$12                          ; dos_opendir
+	sta HTRAP00
+	+nop
+
+	; XXX handle read errors
+
+	sta SD_DESC                       ; store directory descriptor  XXX invent better name
+
+	; Reset status to OK
+
+	lda #$00
+	sta PAR_TRACK
+	sta PAR_SECTOR
+	jsr util_status_SD
+
+	; XXX deduplicate part above with opening directory
+
+	; Read dirent structures into $1000, find the first matching file
+	; Starting at $1000 VIC sees chargen, so this should be a safe place
+
+	jsr fs_hvsr_direntmem_prepare
+
+@lp_find:
+
+	jsr fs_hvsr_util_nextdirentry      ; fetch the next file name
+	+bcs fs_hvsr_file_not_found
+
+	; Only accept files of type 'PRG'
+
+	lda PAR_FTYPE
+	and #%10111111 
+	cmp #$02
+	bne @lp_find
+
+	; Check if file name matches the filter
+
+	jsr util_dir_filter
+	bne @lp_find                       ; if does not match, try the next entry
+
+	; Found the file - load it
+
+	; XXX provide implementation
+
+
+
+	clc
+	rts
+
+fs_hvsr_file_not_found:
+
+	jsr fs_hvsr_direntmem_restore     ; restore $1000 memory content
+
+    ldx SD_DESC
+	lda #$16                          ; dos_closedir
+	sta HTRAP00
+	+nop
+
+	lda #39                           ; file not found error
+	jsr util_status_SD
+
+	sec
+	rts