From adecc6f859c75ae3fcc31a2f0924296607f8411c Mon Sep 17 00:00:00 2001
From: "B. Watson" <yalhcru@gmail.com>
Date: Thu, 25 Feb 2016 02:16:29 -0500
Subject: cart build now only uses 4 banks, next commit will switch to a 32K
 cart

---
 bank7.s | 66 ++++++++++++++++++++++++++++++++++++++++++++---------------------
 1 file changed, 45 insertions(+), 21 deletions(-)

(limited to 'bank7.s')

diff --git a/bank7.s b/bank7.s
index 32e5a34..4b8e207 100644
--- a/bank7.s
+++ b/bank7.s
@@ -30,12 +30,13 @@ screendata:
  ; uncompressed title screen bitmap, $1700 bytes
  .incbin "titledata.dat"
 
- .res $44, $ff ; fudge factor, keep the DL from crossing a 1K boundary
+ ;.out .sprintf("next byte after titledata is %x", *)
 
- ; newtitle.s is the display list and menu code. CART_TARGET is used
- ; for conditional assembly (to make it work from ROM).
-CART_TARGET = 1
- .include "newtitle.s"
+; message to print when someone tries to boot the cart
+; in a 16K Atari.
+mem_msg:
+ scrcode "Need at least 32K"
+mem_msg_len = * - mem_msg - 1
 
 ; copy_31_pages:
 ; copy 7936 bytes from $8000-$9dff to (destptr).
@@ -44,14 +45,19 @@ CART_TARGET = 1
 ; copy_x_pages:
 ; as above, but accepts number of pages to copy in X register.
 
+; copy_pages:
+; as copy_x_pages, but the caller must set up srcptr as well
+; as the X reg.
+
 copy_31_pages:
  ldx #$1f
 copy_x_pages:
  lda #$0
- tay
  sta srcptr
  lda #$80
  sta srcptr+1
+copy_pages:
+ ldy #0
 @copypage:
  lda (srcptr),y
  sta (destptr),y
@@ -64,10 +70,6 @@ copy_x_pages:
 init:
  rts
 
-mem_msg:
- scrcode "Sorry, this game requires at least 32K"
-mem_msg_len = * - mem_msg - 1
-
 memory_error:
  lda #$20 ; red BG
  sta COLOR2
@@ -80,11 +82,21 @@ memory_error:
 @hang:
  bmi @hang
 
+ .out .sprintf("fudge factor: %d bytes", $b744-*)
+ .res $b744-*, $ff ; fudge factor, keep the DL from crossing a 1K boundary
+
+ ; newtitle.s is the display list and menu code. CART_TARGET is used
+ ; for conditional assembly (to make it work from ROM).
+CART_TARGET = 1
+ .include "newtitle.s"
+
 cartstart:
  lda RAMTOP
  cmp #$80
- bne memory_error
+ beq mem_ok
+ jmp memory_error
 
+mem_ok:
 ; turn off ANTIC DMA to speed up copying to RAM
  lda #0
  sta SDMCTL
@@ -107,10 +119,19 @@ cartstart:
  sta CCNTL ; ...select it
  jsr copy_31_pages
 
- lda #2    ; bank 2...
- sta CCNTL ; ...select it
- ldx #(>BANK2SIZE)+1 ; BANK2SIZE defined on the command line
- jsr copy_x_pages
+ ;lda #2    ; bank 2...
+ ;sta CCNTL ; ...select it
+ ;ldx #(>BANK2SIZE)+1 ; BANK2SIZE defined on the command line
+ ;jsr copy_x_pages
+ ;.out .sprintf("BANK2SIZE $%x (%d pages)", BANK2SIZE, (>BANK2SIZE)+1)
+
+ ; tail end of the code is now stored in this bank instead of bank 2.
+ lda #<code_tail
+ sta srcptr
+ lda #>code_tail
+ sta srcptr+1
+ ldx #(>code_tail_size)+1
+ jsr copy_pages
 
  ; bank 3 contains our font, RODATA, and some code that runs from ROM
  ; rather than being copied to RAM. It stays enabled the entire time
@@ -118,18 +139,21 @@ cartstart:
  lda #3    ; bank 3...
  sta CCNTL ; ...select it
 
- .out .sprintf("BANK2SIZE $%x (%d pages)", BANK2SIZE, (>BANK2SIZE)+1)
-
  lda #1
  sta COLDST    ; System Reset = reboot
  jsr start     ; 'start' is from newtitle.s
  jsr codedest  ; run the game (romable_taimain)
  jmp cartstart ; redisplay title screen if "play again? N"
 
+code_tail:
+ .incbin "splitrom.raw.2"
+ code_tail_size = * - code_tail + 1
+ .out .sprintf("code_tail_size $%x (%d pages)", code_tail_size, (>code_tail_size)+1)
+
  .if * > cart_trailer
   .fatal "bank7 code too large"
  .else
-  .out .sprintf("=> %d bytes free in bank 7", cart_trailer - *)
+  .out .sprintf("=> %d bytes free in bank 7, at %x", cart_trailer - *, *)
  .endif
 
  ; fill with 1 bits until the cart trailer
@@ -140,6 +164,6 @@ cartstart:
  ; see Mapping the Atari's entry for 'Cartridge B' or the Tech Ref Manual
  ; for a description of this.
  .word cartstart ; entry point
- .byte 0     ; 0 = cartridge present
- .byte 4     ; init and run the cart, don't boot the disk, non-diagnostic
- .word init  ; init address (just an RTS)
+ .byte 0         ; 0 = cartridge present
+ .byte 4         ; init and run the cart, don't boot the disk, non-diagnostic
+ .word init      ; init address (just an RTS)
-- 
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