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-rw-r--r--dla.s48
1 files changed, 42 insertions, 6 deletions
diff --git a/dla.s b/dla.s
index e1429e9..130659f 100644
--- a/dla.s
+++ b/dla.s
@@ -12,6 +12,7 @@
.include "nextpage.inc"
loadaddr = $2000
+ lowcode = $0600 ; memcheck and io.s
screen = $4000 ; must be on a x000 (4K) boundary
screen2 = screen + $1000 ; rest of screen RAM after 4K boundary
pixarray = screen + $20
@@ -52,9 +53,39 @@ cloksav: .res 3 ; hold RTCLOK here while we convert to MM:SS.CC
fptmp: .res 6 ; used in mmss.s
.code
- xex_org loadaddr
+
+ ;;; init xex segment: check that there's enough memory.
+ xex_org lowcode
.include "io.s" ; printchrx and getchrx
.include "printint.s"
+
+memcheck:
+ lda RAMTOP
+ cmp #$c0 ; 48K
+ bcs mem_ok
+ lda #<memmsg
+ ldx #>memmsg
+ jsr printmsg
+ lda RAMTOP ; free RAM in pages, divide by 4 to get K
+ lsr
+ lsr
+ jsr printdecb
+ lda #<memmsg2
+ ldx #>memmsg2
+ jsr printmsg
+mem_bad:
+ jmp mem_bad ; TODO: find a way to return to DOS from here
+mem_ok:
+ rts
+
+memmsg: .byte "Need 48K, only have ",0
+memmsg2: .byte "K.",$9b,"Disable BASIC, remove cartridge?",$9b,0
+
+ xex_init memcheck
+
+ ;;; main xex segment: the actual program. the functions in io.s
+ ;;; and printint.s are still in low memory.
+ xex_org loadaddr
.include "mmss.s"
; init stuff gets done once, at startup
@@ -453,6 +484,8 @@ plot:
sta (pixptr),y
rts
+ ; drunkwalk is less than a page long. nextpage macro starts it
+ ; on a page boundary, so branches don't cost an extra cycle.
nextpage
.include "drunkwalk.s"
@@ -631,9 +664,10 @@ seeds_h: .byte >(seed_point-1),>(seed_plus-1),>(seed_4pt-1),>(seed_long-1)
; dlatbl.s is generated by perl script, mkdlatbl.pl
.include "dlatbl.s"
- ; table of addresses, for each line on the screen. bloats the
- ; code by 384 bytes, but compared to calculating the address, is
- ; twice as fast!
+ ; table of addresses, for each line on the screen.
+ ; these 2 tables (low and high bytes) are less than a page each.
+ ; nextpage macro guarantees they don't cross a page boundary (so
+ ; indexed addressing doesn't cost an extra cycle).
nextpage
lineaddrs_l:
laddr .set pixarray
@@ -653,6 +687,7 @@ lineaddrs_h:
;;; display list
; ANTIC opcodes
blank8 = $70
+ blank3 = $20
gr8 = $0f
gr0 = $02
lms = $40
@@ -660,7 +695,7 @@ lineaddrs_h:
xex_org dlist
.byte blank8, blank8, blank8
- .byte blank8
+ .byte blank8, blank3
.byte gr8 | lms
.word screen
.repeat 127
@@ -668,9 +703,10 @@ lineaddrs_h:
.endrep
.byte gr8 | lms
.word screen2
- .repeat maxlines - 132
+ .repeat maxlines - 129
.byte gr8
.endrep
+ .byte blank3
.byte gr0 | lms
.word textbuf
.byte jvb