From 0e34cd8d68c0687d970940d8342768827f501cbb Mon Sep 17 00:00:00 2001
From: FeralChild64 <you@example.com>
Date: Fri, 26 Mar 2021 21:43:24 +0100
Subject: [PATCH] more work on RAM disk support, added ATTIC/CELLAR RAM test

---
 src/aliases/,aliases_ram_lowmem.s          |   2 +-
 src/dos_m65/,aliases_dos.s                 |   7 +-
 src/dos_m65/4020.dos_vectable.s            |   1 +
 src/dos_m65/dos_preload.s                  |  17 ++++
 src/dos_m65/unit_ramdisk/unit_rd_init.s    | 102 ++++++++++++++++-----
 src/dos_m65/unit_ramdisk/unit_rd_preload.s |  47 ++++++++++
 src/kernal/iec_fast/m65dos_bridge.s        |  31 ++++---
 src/kernal/init/fce2.hw_entry_reset.s      |   2 +
 8 files changed, 174 insertions(+), 35 deletions(-)
 create mode 100644 src/dos_m65/dos_preload.s
 create mode 100644 src/dos_m65/unit_ramdisk/unit_rd_preload.s

diff --git a/src/aliases/,aliases_ram_lowmem.s b/src/aliases/,aliases_ram_lowmem.s
index ed03d9c9..2c6e08db 100644
--- a/src/aliases/,aliases_ram_lowmem.s
+++ b/src/aliases/,aliases_ram_lowmem.s
@@ -44,7 +44,7 @@
 	!addr OLDLIN    = $3B ; $3B-$3C  previous BASIC line number
 	!addr OLDTXT    = $3D ; $3D-$3E  current BASIC line pointer
 	!addr DATLIN    = $3F ; $3F-$40  -- NOT IMPLEMENTED --
-	!addr DATPTR    = $41 ; $41-$42  pointer for READ/DATA copmmands
+	!addr DATPTR    = $41 ; $41-$42  pointer for READ/DATA commands
 	!addr INPPTR    = $43 ; $43-$44  -- NOT IMPLEMENTED --
 	!addr VARNAM    = $45 ; $45-$46  current variable name
 	!addr VARPNT    = $47 ; $47-$48  current variable/descriptor pointer
diff --git a/src/dos_m65/,aliases_dos.s b/src/dos_m65/,aliases_dos.s
index e5652ce5..2be9d441 100644
--- a/src/dos_m65/,aliases_dos.s
+++ b/src/dos_m65/,aliases_dos.s
@@ -27,7 +27,12 @@
 	!addr REG_Y            = $8007
 	!addr REG_Z            = $8008
 
-	; Reserved: $8009 - $800C
+	; System configuration
+
+	!addr RAM_ATTIC        = $8009 ; $8000000-$87FFFFF RAM status; 0 = not present, $FF = present
+	!addr RAM_CELLAR       = $800A ; $8800000-$8FFFFFF RAM status; 0 = not present, $FF = present
+
+	; Reserved: $800B - $800C
 
 	; General DOS configuration
 
diff --git a/src/dos_m65/4020.dos_vectable.s b/src/dos_m65/4020.dos_vectable.s
index fb940b73..fd2aa2c3 100644
--- a/src/dos_m65/4020.dos_vectable.s
+++ b/src/dos_m65/4020.dos_vectable.s
@@ -2,6 +2,7 @@
 ; A vector table to integrate DOS with the MEGA65 Kernal
 
 !word dos_INIT
+!word dos_PRELOAD
 !word dos_UNITCHK
 !word dos_UNITSET
 !word dos_UNITNUM
diff --git a/src/dos_m65/dos_preload.s b/src/dos_m65/dos_preload.s
new file mode 100644
index 00000000..0775e180
--- /dev/null
+++ b/src/dos_m65/dos_preload.s
@@ -0,0 +1,17 @@
+
+;
+; Preload RAM disk image
+;
+
+
+dos_PRELOAD:
+
+	; Before the start make sure memory content is not damaged
+
+	jsr dos_MEMCHK
+	bcc @ok
+	rts
+@ok:
+	jsr dos_ENTER
+	jsr unit_rd_preload
+	jmp dos_EXIT_CLC
diff --git a/src/dos_m65/unit_ramdisk/unit_rd_init.s b/src/dos_m65/unit_ramdisk/unit_rd_init.s
index bff58927..eeb9826f 100644
--- a/src/dos_m65/unit_ramdisk/unit_rd_init.s
+++ b/src/dos_m65/unit_ramdisk/unit_rd_init.s
@@ -1,11 +1,12 @@
 
 ;
-; Initializes DOS part of ram disk
+; Initializes DOS part of RAM disk
 ;
 
 
 unit_rd_init:
 
+
 	; Copy status string
 
 	ldx #$00
@@ -23,41 +24,98 @@ unit_rd_init:
 	sta RD_STATUS_BUF,x
 	bne @1
 
-	; End of initialization, now try to load the initial RAM disk; first set file name
+	; FALLTROUGH
 
-	ldy #>ramdisk_filename
-	ldx #<ramdisk_filename
-	lda #$2E                           ; dos_setname
-	sta HTRAP00
-	+nop
-	bcc @error_not_found
+unit_rd_init_test_ram:                 ; non-destructive ATTIC/CELLAR RAM test
 
-	; Try to find the file
+	; Preserve temporary address area on stack
 
-	lda #$34                           ; dos_findfile
-	sta HTRAP00
-	+nop
-	bcc @error_not_found               ; branch if file not found    XXX why it can't find the file?
+	ldx #$03
+@2:
+	lda PNTR, x
+	pha
+	dex
+	bpl @2
 
-	; XXX load the file
+	; For the start, mark extended RAM as not present
 
+	inx
+	stx RAM_ATTIC                      ; set ATTIC/CELLAR RAM as not present
+	stx RAM_CELLAR
 
-;@x:
-;	inc $D020
-;	bra @x
+	; Prepare address - ATTIC RAM, $0800:$0000
 
+	stx PNTR+0
+	stx PNTR+1
+	stx PNTR+2
+	lda #$08
+	sta PNTR+3
 
-	; lda #$20                           ; dos_closefile
-	; sta HTRAP00
-	; +nop
+	ldz #$00
+
+	; Test for ATTIC RAM
+
+	jsr @perform_ram_test
+	bne @done_attic
+	dec RAM_ATTIC                      ; test passed
+
+@done_attic:
+
+	; Prepare address - CELLAR RAM, $0880:$0000
+
+	lda #$80
+	sta PNTR+2
+
+	; Test for cellar RAM
+
+	jsr @perform_ram_test
+	bne @done_cellar
+	dec RAM_CELLAR                     ; test passed
+
+@done_cellar:
+
+	; Restore temporary address area content
+
+	ldx #$00
+@3:
+	pla
+	sta PNTR, x
+	inx
+	cpx #$04
+	bne @3
 
 	; End of initialization
 
 	rts
 
+@perform_ram_test:
 
-@error_not_found:
+	; Try to change one byte in extended RAM
 
-	; XXX set information about file not found
+	lda [PNTR], z
+	tax
+	eor #$FF
+	sta [PNTR], z
 
+	; Make sure the cache does not contain the value any more
+
+	tay
+	dez
+	lda [PNTR], z
+	inz
+	tya
+
+	; Check if byte still contains the new value
+
+	cmp [PNTR], z
+	php
+
+	; Restore byte content
+
+	txa
+	sta [PNTR], z
+	
+	; Return test result
+
+	plp
 	rts
diff --git a/src/dos_m65/unit_ramdisk/unit_rd_preload.s b/src/dos_m65/unit_ramdisk/unit_rd_preload.s
new file mode 100644
index 00000000..0facd81b
--- /dev/null
+++ b/src/dos_m65/unit_ramdisk/unit_rd_preload.s
@@ -0,0 +1,47 @@
+
+;
+; Preload RAM disk image from SD card
+;
+
+
+unit_rd_preload:
+
+	; XXX make sure attic RAM is present
+
+	rts ; XXX remove when code is fully implemented
+
+	; Set file name
+
+	ldy #>ramdisk_filename
+	ldx #<ramdisk_filename
+	lda #$2E                           ; dos_setname
+	sta HTRAP00
+	+nop
+	bcc @error_not_found
+
+	; Try to find the file
+
+	lda #$34                           ; dos_findfile
+	sta HTRAP00
+	+nop
+	bcc @error_not_found               ; branch if file not found
+
+	; XXX load the file
+
+
+
+
+	; lda #$20                           ; dos_closefile
+	; sta HTRAP00
+	; +nop
+
+	; End of initialization
+
+	rts
+
+
+@error_not_found:
+
+	; XXX set information about file not found
+
+	rts
diff --git a/src/kernal/iec_fast/m65dos_bridge.s b/src/kernal/iec_fast/m65dos_bridge.s
index 7e7643c1..9d60ffc5 100644
--- a/src/kernal/iec_fast/m65dos_bridge.s
+++ b/src/kernal/iec_fast/m65dos_bridge.s
@@ -7,17 +7,18 @@
 
 
 !addr VDOS_INIT    = $4020 +  0 * 2
-!addr VDOS_UNITCHK = $4020 +  1 * 2
-!addr VDOS_UNITSET = $4020 +  2 * 2
-!addr VDOS_UNITNUM = $4020 +  3 * 2
-!addr VDOS_ACPTR   = $4020 +  4 * 2
-!addr VDOS_CIOUT   = $4020 +  5 * 2
-!addr VDOS_LISTEN  = $4020 +  6 * 2
-!addr VDOS_SECOND  = $4020 +  7 * 2
-!addr VDOS_TALK    = $4020 +  8 * 2
-!addr VDOS_TKSA    = $4020 +  9 * 2
-!addr VDOS_UNTLK   = $4020 + 10 * 2
-!addr VDOS_UNLSN   = $4020 + 11 * 2
+!addr VDOS_PRELOAD = $4020 +  1 * 2
+!addr VDOS_UNITCHK = $4020 +  2 * 2
+!addr VDOS_UNITSET = $4020 +  3 * 2
+!addr VDOS_UNITNUM = $4020 +  4 * 2
+!addr VDOS_ACPTR   = $4020 +  5 * 2
+!addr VDOS_CIOUT   = $4020 +  6 * 2
+!addr VDOS_LISTEN  = $4020 +  7 * 2
+!addr VDOS_SECOND  = $4020 +  8 * 2
+!addr VDOS_TALK    = $4020 +  9 * 2
+!addr VDOS_TKSA    = $4020 + 10 * 2
+!addr VDOS_UNTLK   = $4020 + 11 * 2
+!addr VDOS_UNLSN   = $4020 + 12 * 2
 
 
 m65dos_init:
@@ -28,6 +29,14 @@ m65dos_init:
 	jsr (VDOS_INIT)
 	bra m65dos_end_1
 
+m65dos_preload:
+
+	; Preaload RAM disk content, only to be used during KERNAL initialization
+
+	jsr map_DOS_1
+	jsr (VDOS_PRELOAD)
+	bra m65dos_end_1
+
 m65dos_unitchk:                        ; XXX expose to BASIC
 
 	; Checks is the unit number is supported by the internal DOS
diff --git a/src/kernal/init/fce2.hw_entry_reset.s b/src/kernal/init/fce2.hw_entry_reset.s
index 3f4ac748..33ef4ace 100644
--- a/src/kernal/init/fce2.hw_entry_reset.s
+++ b/src/kernal/init/fce2.hw_entry_reset.s
@@ -64,6 +64,8 @@ hw_entry_reset:
 
 	jsr m65_reset_common     ; RAMTAS, RESTOR, CINT
 
+	jsr m65dos_preload       ; preload RAM disk content
+
 	clc
 	jsr M65_MODESET          ; on MEGA65 go to native mode by default