file loading from floppy image should be complete, but not yet tested

src/dos_m65/filesystem_cbm/fs_cbm_nextdirentry.s

@@ -49,7 +49,14 @@ fs_cbm_nextdirentry:
 	; XXX most likely copying is not necessary (compare all CBM and CMD filesystems) -
 	; XXX just make the hypervisor file system emulate these structures
 
-	ldy #$02                           ; start from determining file type
+	ldy #$00                           ; start from getting track and sector of file beginning
+	jsr code_LDA_nnnn_Y
+	sta FD_LOADTRACK
+	iny
+	jsr code_LDA_nnnn_Y
+	sta FD_LOADSECTOR
+
+	iny                                ; determining file type
 	jsr code_LDA_nnnn_Y
 	beq fs_cbm_nextdirentry            ; ignore deleted files (but allow DEL files in some cases)
 

src/dos_m65/filesystem_cbm/fs_cbm_read_file.s

@@ -48,19 +48,108 @@ fs_cbm_read_file_open:
 	jsr util_dir_filter
 	bne @lp_find                       ; if does not match, try the next entry
 
-	; Found the file - load it, start from fetching initial track/sector
+	; Found the file, load it
 
-	inc $D020
+	lda FD_LOADTRACK
+	sta PAR_TRACK
+	lda FD_LOADSECTOR
+	sta PAR_SECTOR
 
-
-
-
-	; XXX provide implementation, use FD_LOADTRACK and FD_LOADSECTOR
-
-	jmp dos_EXIT_SEC
+	bra fs_cbm_read_file_got_ts
 
 fs_cbm_read_file:
 
-	; XXX provide implementation
+	; Fetch the next track/sector
 
-	jmp dos_EXIT_SEC
+	lda FD_LOADSECTOR
+	and #$01
+	bne @part_2
+
+@part_1:
+
+	; We were reading from the 1st half of the buffer
+
+	lda SHARED_BUF_1+1
+	sta PAR_SECTOR
+	lda SHARED_BUF_1+0
+	bra @common_chk
+
+@part_2:
+
+	; We were reading from the 2nd half of the buffer
+
+	lda SHARED_BUF_1+$100+1
+	sta PAR_SECTOR
+	lda SHARED_BUF_1+$100+0
+
+@common_chk:
+
+	bne @common_load
+
+	lda #$00                           ; end of file
+	sec
+	rts
+
+@common_load:
+
+	sta PAR_TRACK
+
+	; FALLTROUGH
+
+fs_cbm_read_file_got_ts:
+
+	; Load next track/sector
+
+	jsr lowlevel_readsector         ; XXX handle read errors
+
+	; Store pointer and amount of data ready to fetch
+
+	lda #$FE
+	sta FD_ACPTR_LEN+0
+	lda #$00
+	sta FD_ACPTR_LEN+1
+
+	lda #$02
+	sta FD_ACPTR_PTR+0
+	lda #>SHARED_BUF_1
+	sta FD_ACPTR_PTR+1
+
+	lda PAR_SECTOR
+	and #$01
+	bne @part_2
+
+@part_1:
+
+	; Sector with data is located in the 1st half of the buffer
+
+	lda SHARED_BUF_1+0
+	beq @exit
+
+	; Less than a full sector is used
+
+	lda SHARED_BUF_1+1
+	bra @not_full_buf
+
+@part_2:
+
+	; Sector with data is located in the 2nd half of the buffer
+
+	inc FD_ACPTR_PTR+1
+
+	lda SHARED_BUF_1+$100+0
+	beq @exit
+
+	; Less than a full sector is used
+
+	lda SHARED_BUF_1+$100+0
+
+@not_full_buf:
+
+	sta FD_ACPTR_LEN+0
+
+	; FALLTROUGH
+
+@exit:
+
+	clc
+	rts