From cf9d37dba8f93e903b8af682a5a17192df85e4a7 Mon Sep 17 00:00:00 2001
From: mgcaret <mgcaret@users.noreply.github.com>
Date: Fri, 27 Dec 2019 13:38:13 -0800
Subject: [PATCH] GoSXB: stub ROM to launch OF816 at bank

---
 .gitignore                     |  1 +
 platforms/GoSXB/GoSXB.l        |  1 -
 platforms/GoSXB/build.sh       |  4 ++-
 platforms/GoSXB/platform-lib.s | 21 ++++++++--------
 platforms/GoSXB/romboot.l      | 15 ++++++++++++
 platforms/GoSXB/romboot.s      | 45 ++++++++++++++++++++++++++++++++++
 6 files changed, 74 insertions(+), 13 deletions(-)
 create mode 100644 platforms/GoSXB/romboot.l
 create mode 100644 platforms/GoSXB/romboot.s

diff --git a/.gitignore b/.gitignore
index 991145c..cfe9160 100644
--- a/.gitignore
+++ b/.gitignore
@@ -12,4 +12,5 @@ romfs
 .DS_Store
 *.hex
 of816-neon.bin
+platforms/GoSXB/rom
 
diff --git a/platforms/GoSXB/GoSXB.l b/platforms/GoSXB/GoSXB.l
index a68b674..a758050 100644
--- a/platforms/GoSXB/GoSXB.l
+++ b/platforms/GoSXB/GoSXB.l
@@ -13,4 +13,3 @@ SEGMENTS {
 	FCode: load=ROM, type=ro, optional=yes;
 	ZEROPAGE: load=ZP, type=bss;
 }
-
diff --git a/platforms/GoSXB/build.sh b/platforms/GoSXB/build.sh
index c2b0a45..820145f 100755
--- a/platforms/GoSXB/build.sh
+++ b/platforms/GoSXB/build.sh
@@ -3,5 +3,7 @@ set -e -x
 ca65 -I ../../inc GoSXB.s -l GoSXB.lst
 ../../build.sh GoSXB
 ld65 -C GoSXB.l -S 0x8000 GoSXB.o ../../forth.o -m forth.map -o forth
-ls -l forth
+ca65 -I ../../inc romboot.s -l romboot.lst
+ld65 -C romboot.l -S 0x0000 romboot.o -m romboot.map -o rom
+ls -l rom forth
 
diff --git a/platforms/GoSXB/platform-lib.s b/platforms/GoSXB/platform-lib.s
index 0351048..410ada5 100644
--- a/platforms/GoSXB/platform-lib.s
+++ b/platforms/GoSXB/platform-lib.s
@@ -91,7 +91,7 @@ table:    .addr _sf_pre_init
 
 
 .proc     _sf_pre_init
-.if 1
+.if 0
           plx
           jmp   _sf_success     ; assume WDC monitor already did it
 .else
@@ -101,25 +101,24 @@ table:    .addr _sf_pre_init
           .a8
           .i8
           lda   #$00
-          sta   VIA2+VIA::ACR
-          lda   #$00
-          sta   VIA2+VIA::PCR
+          sta   f:VIA2+VIA::ACR
+          sta   f:VIA2+VIA::PCR
           lda   #%00011000      ; b3 = TUSB_RDB; b4 = ???
-          sta   VIA2+VIA::ORB
+          sta   f:VIA2+VIA::ORB
           lda   #%00011100      ; set PB2, PB3, PB4 as outputs
-          sta   VIA2+VIA::DDRB
+          sta   f:VIA2+VIA::DDRB
           lda   #$00
           sta   VIA2+VIA::DDRA
           lda   VIA2+VIA::IRB
           pha
           and   #%11101111      ; b4 = ???
-          sta   VIA2+VIA::ORB
+          sta   f:VIA2+VIA::ORB
           ldx   #$5d
           jsr   wait
           pla
-          sta   VIA2+VIA::ORB
-          lda   #%00100000      ; b5 = TUSB_PWRENB
-:         bit   VIA2+VIA::IRB   ; wait for USB configuration
+          sta   f:VIA2+VIA::ORB
+:         lda   f:VIA2+VIA::IRB   ; wait for USB configuration
+          bit   #%00100000      ; b5 = TUSB_PWRENB
           bne   :-
           plp
           plx
@@ -179,7 +178,7 @@ wait:     phx                   ; note 8-bit mode!
           txa
           sta   f:VIA2+VIA::ORB ; strobe FT245RL WR low
           lda   VIA2+VIA::IRA   ; get output byte back (we don't really need it)
-	  xba
+	      xba
           lda   #$00
           sta   f:VIA2+VIA::DDRA  ; switch DDR A back to input
           xba
diff --git a/platforms/GoSXB/romboot.l b/platforms/GoSXB/romboot.l
new file mode 100644
index 0000000..3461c77
--- /dev/null
+++ b/platforms/GoSXB/romboot.l
@@ -0,0 +1,15 @@
+# Note this linker config relies on the fact that bank 3
+# in the output file has the same lower 16 bit addresses
+# as the run location.  You can't use it to link relative
+# code into bank 0 or bank 2
+
+MEMORY {
+    MAINMEM: start = $0000, size=$10000;
+	ROM: start = $000000, size = $020000, fillval=$FF, file = %O;
+	ZP: start = $0000, size = $100;
+}
+
+SEGMENTS {
+    ROMBOOT: load=ROM, run=ROM, start=$1FF00, type=ro;
+    VECTORS: load=ROM, run=ROM, start=$1FFE0, type=ro;
+}
diff --git a/platforms/GoSXB/romboot.s b/platforms/GoSXB/romboot.s
new file mode 100644
index 0000000..4433a5a
--- /dev/null
+++ b/platforms/GoSXB/romboot.s
@@ -0,0 +1,45 @@
+.p816
+.a16
+.i16
+.include  "macros.inc"
+
+.segment  "ROMBOOT"
+.proc     romboot
+          jml   f:$200000
+.endproc
+
+.proc     emuirq
+          pha
+          lda   2,s
+          and   #%00100000
+          bne   romboot           ; if BRK, handle like we reset.
+          pla                     ; in case we want to RTI or something in the future
+          ; fall-through
+.endproc
+
+.proc     die
+          wdm   $FF               ; GoSXB will exit
+hang:     bra   hang              ; Anything else will hang
+.endproc
+
+.segment  "VECTORS"
+.proc     vectors
+          ; native mode vectors
+          .word $FFFF             ; FFE0 - reserved
+          .word $FFFF             ; FFE2 - reserved
+          .word .loword(die)      ; FFE4 - COP
+          .word .loword(romboot)  ; FFE6 - BRK
+          .word .loword(die)      ; FFE8 - ABORT
+          .word .loword(romboot)  ; FFEA - NMI
+          .word $FFFF             ; FFEC - reserved
+          .word .loword(die)      ; FFEE - IRQ
+          ; emulation mode vectors
+          .word $FFFF             ; FFF0 - reserved
+          .word $FFFF             ; FFF2 - reserved
+          .word .loword(die)      ; FFF4 - COP
+          .word $FFFF             ; FFF6 - reserved
+          .word .loword(die)      ; FFF8 - ABORT
+          .word .loword(romboot)  ; FFFA - NMI
+          .word .loword(romboot)  ; FFFC - RESET
+          .word .loword(emuirq)   ; FFFE - IRQ/BRK
+.endproc