more work towards preloading RAM disk image

src/dos_m65/,aliases_dos.s

@@ -138,10 +138,12 @@
 	!addr F1_LOADTRACK     = $807D ; current track for file loading
 	!addr F1_LOADSECTOR    = $807E ; current sector for file loading
 
-	!addr RD_STARTSEG      = $807F ; RAM disk start address, 2nd most significant byte (or $FF if no RAM)
-	!addr RD_MAXTRACK      = $8080 ; maximum RAM disk track number
+	!addr RD_MAXTRACK      = $807F ; maximum RAM disk track number of loaded image
+	!addr RD_STARTSEG      = $8080 ; RAM disk start address, 2nd most significant byte (or $FF if no RAM)
+	!addr RD_VALIDIMG      = $8081 ; $00 = no valid image loaded
 
-	; Reserved: $8081-$81FF
+
+	; Reserved: $8082-$81FF
 
 	;
 	; Various buffers, caches, and other large memory chunks

src/dos_m65/unit_ramdisk/unit_rd_init.s

@@ -41,7 +41,7 @@ unit_rd_init_test_ram:                 ; non-destructive ATTIC/CELLAR RAM test
 
 	stx RD_STARTSEG                    ; by default $FF, to mark no RAM disk
 	inx
-	stx RD_MAXTRACK                    ; maximum allowed track number, for now set 0
+	stx RD_VALIDIMG                    ; mark no valid image loaded
 	stx RAM_ATTIC                      ; set ATTIC/CELLAR RAM as not present
 	stx RAM_CELLAR
 

src/dos_m65/unit_ramdisk/unit_rd_preload.s

@@ -4,17 +4,22 @@
 ;
 
 
+!addr __stoptrack = RD_DIR_PHASE       ; helper value for detecting too large image
+
+
 unit_rd_preload:
 
-	; Check if RAM disk is enabled
+	; Check if RAM disk is enabled (should be disabled if no Hyper RAM is present)
 
 	lda UNIT_RAMDISK
 	beq @error_no_ramdisk
 
-	; XXX make sure attic RAM is present
-
 	rts ; XXX remove when code is fully implemented
 
+
+
+
+
 	; Set file name
 
 	ldy #>ramdisk_filename
@@ -31,6 +36,30 @@ unit_rd_preload:
 	+nop
 	bcc @error_not_found               ; branch if file not found
 
+	; Calculate maximum amount of tracks possible to load
+
+	lda #$FF
+	sta RD_MAXTRACK                    ; maximum track number of loaded image, for now set $FF
+	sta __stoptrack
+
+	lda RAM_ATTIC
+	beq @added_attic
+	jsr unit_rd_preload_addram
+
+@added_attic:
+
+	lda RAM_CELLAR
+	beq @added_cellar
+	jsr unit_rd_preload_addram
+
+@added_cellar:
+
+	; Load the file
+
+
+
+
+
 	; XXX load the file
 
 	; XXX while loading set RD_MAXTRACK
@@ -47,6 +76,12 @@ unit_rd_preload:
 
 	; End of initialization
 
+	lda #$FF
+	sta RD_VALIDIMG                      ; mark image as valid
+
+	lda #$00                             ; temporary storage needs to be restored to 0
+	sta __stoptrack
+
 	rts
 
 
@@ -61,3 +96,17 @@ unit_rd_preload:
 	; XXX set error information
 
 	rts
+
+
+
+
+
+unit_rd_preload_addram:
+
+	; Add allowed number of tracks due to attic/cellar block presence
+
+	clc
+	lda #$80
+	adc __stoptrack
+	sta __stoptrack
+	rts