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Upgraded the cx16 library to the Commander X16 Kernal ROM's prerelease 39.

This commit is contained in:
Greg King 2022-04-02 09:39:35 -04:00
parent 75ee10478e
commit a5e69e7ea6
18 changed files with 208 additions and 172 deletions
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9
asminc/cbm_kernal.inc
View File

@ -7,8 +7,13 @@
.if .def(__CX16__)
; CX16 extended jump table
KBDBUF_PEEK := $FEBD
KBDBUF_GET_MODIFIERS := $FEC0
KBDBUF_PUT := $FEC3
I2C_READ_BYTE := $FEC6
I2C_WRITE_BYTE := $FEC9
CX_MONITOR := $FECC
ENTROPY_GET := $FECF
KEYBRD_BUF_PUT := $FED2
CONSOLE_SET_PAGE_MSG := $FED5
CONSOLE_PUT_IMAGE := $FED8
CONSOLE_INIT := $FEDB
@ -52,7 +57,7 @@
CLOCK_GET_DATE_TIME := $FF50
JOYSTICK_SCAN := $FF53
JOYSTICK_GET := $FF56
SCREEN_SET_MODE := $FF5F
SCREEN_MODE := $FF5F
SCREEN_SET_CHARSET := $FF62
MOUSE_CONFIG := $FF68
MOUSE_GET := $FF6B

104
asminc/cx16.inc
View File

@ -1,5 +1,5 @@
;
; CX16 r38 definitions
; CX16 r39 definitions
;
; ---------------------------------------------------------------------------
@ -106,6 +106,10 @@ PI
; ---------------------------------------------------------------------------
; Zero page
; Banking registers
RAM_BANK := $00
ROM_BANK := $01
; GEOS and graphics pseudo-registers
.struct gREG
.org $02
@ -226,7 +230,7 @@ PI
; Kernal
KTEMP2 := $80 ; 2 bytes for temporary storage
IMPARM := $82 ; Pointer for PRIMM function
FNAM := $8C ; Pointer to filename
FNAM := $8A ; Pointer to filename
; BASIC
TXTPTR := $EE ; Pointer into BASIC source code
@ -236,14 +240,13 @@ TXTPTR := $EE ; Pointer into BASIC source code
BASIC_BUF := $0200 ; Location of command-line
BASIC_BUF_LEN = 81 ; Maximum length of command-line
SCREEN_MODE := $0261 ; Current screen mode (set by SCREEN_SET_MODE)
SCREEN_PTR := $0262 ; Pointer to current row on text screen (16 bits)
STATUS := $0286 ; Status from previous I/O operation
IN_DEV := $028A ; Current input device number
OUT_DEV := $028B ; Current output device number
FNAM_LEN := $028E ; Length of filename
SECADR := $0290 ; Secondary address
DEVNUM := $0291 ; Device number
STATUS := $0289 ; Status from previous I/O operation
IN_DEV := $028D ; Current input device number
OUT_DEV := $028E ; Current output device number
FNAM_LEN := $0291 ; Length of filename
SECADR := $0293 ; Secondary address
DEVNUM := $0294 ; Device number
CURS_COLOR := $0373 ; Color under the cursor
CHARCOLOR := $0376 ; Cursor's color nybbles (high: background, low: foreground)
RVS := $0377 ; Reverse flag
@ -270,6 +273,42 @@ NMIVec := $0318
; ---------------------------------------------------------------------------
; I/O locations
; 65C22 Versatile Interface Adapter
.struct VIA1 ; Versatile Interface Adapter
.org $9F00
PRB .byte ; mouse, LED, VIC bus (Port Register B)
PRA .byte ; keyboard, controllers (Port Register A)
DDRB .byte ; (Data Direction Register B)
DDRA .byte ; (Data Direction Register A)
T1 .word ; (Timer 1)
T1L .word ; (Timer 1 Latch)
T2 .word ; (Timer 2)
SR .byte ; (Shift Register)
ACR .byte ; (Auxiliary Control Register)
PCR .byte ; (Peripheral Control Register)
IFR .byte ; (Interrupt Flags Register)
IER .byte ; (Interrupt Enable Register)
PRA2 .byte ; keyboard, controllers (PRA without handshake)
.endstruct
; 65C22 Versatile Interface Adapter
.struct VIA2
.org $9F10
PRB .byte
PRA .byte
DDRB .byte
DDRA .byte
T1 .word
T1L .word
T2 .word
SR .byte
ACR .byte
PCR .byte
IFR .byte
IER .byte
PRA2 .byte
.endstruct
; Video Enhanced Retro Adapter
; Has audio and SPI.
.scope VERA
@ -498,44 +537,16 @@ NMIVec := $0318
.endstruct
.endscope
; 65C22
.struct VIA1 ; Versatile Interface Adapter
.org $9F60
PRB .byte ; ROM bank, IEC (Port Register B)
PRA .byte ; RAM bank (Port Register A)
DDRB .byte ; (Data Direction Register B)
DDRA .byte ; (Data Direction Register A)
T1 .word ; (Timer 1)
T1L .word ; (Timer 1 Latch)
T2 .word ; (Timer 2)
SR .byte ; (Shift Register)
ACR .byte ; (Auxiliary Control Register)
PCR .byte ; (Peripheral Control Register)
IFR .byte ; (Interrupt Flags Register)
IER .byte ; (Interrupt Enable Register)
PRA2 .byte ; RAM bank (Port Register A without handshaking)
; YM2151 audio chip
.struct YM2151
.org $9F40
.union
STATUS .byte
ADDR .byte
.endunion
DATA .byte
.endstruct
; 65C22
.struct VIA2
.org $9F70
PRB .byte ; Mouse communication ?
PRA .byte ; NES controller communication
DDRB .byte
DDRA .byte
T1 .word
T1L .word
T2 .word
SR .byte
ACR .byte
PCR .byte
IFR .byte
IER .byte
PRA2 .byte
.endstruct
; Real-Time Clock
; X16 Emulator device
; This device doesn't exist on the real machine.
.struct EMULATOR
@ -556,8 +567,7 @@ NMIVec := $0318
; ---------------------------------------------------------------------------
; Banked RAM and ROM
KEY_COUNT := $A00A ; (bank 0) Number of keys in input buffer
TIMER := $A037 ; (bank 0) 60 Hz. timer (3 bytes, big-endian)
TIMER := $A03B ; (bank 0) 60 Hz. timer (3 bytes, big-endian)
.struct BANK
.org $A000

2
cfg/cx16-asm.cfg
View File

@ -1,5 +1,3 @@
# Assembly configuration for R38
FEATURES {
STARTADDRESS: default = $0801;
}

26
doc/cx16.sgml
View File

@ -200,15 +200,23 @@ access to hardware located in the address space. Some variables are
structures, accessing the struct fields will access the chip registers.
<descrip>
<tag><tt/VERA/</tag>
The <tt/VERA/ structure allows access
to the Video Enhanced Retro Adapter chip.
<tag><tt/RAM_BANK/</tag>
A register that controls which bank of high RAM is visible in the
<tt/BANK_RAM/ window.
<tag><tt/ROM_BANK/</tag>
A register that controls which bank of ROM is active at the moment.
<tag><tt/VIA1, VIA2/</tag>
Access to the two VIA (Versatile Interface Adapter) chips is available via
the <tt/VIA1/ and <tt/VIA2/ variables. The structure behind those variables
is explained in <tt/_6522.h/.
<tag><tt/VERA/</tag>
The <tt/VERA/ structure allows access
to the Video Enhanced Retro Adapter chip.
<tag><tt/BANK_RAM/</tag>
A character array that mirrors the eight-Kibibyte window, at &dollar;A000,
into banked RAM.
@ -219,7 +227,7 @@ structures, accessing the struct fields will access the chip registers.
<sect>Loadable drivers<p>
The names in the parentheses denote the symbols to be used for static linking
of the drivers. The names fit into the 8.3 character limit of the SD-Card's
of the drivers. The names fit into the old 8.3-character limit of the SD-Card's
FAT32 file-system.
@ -230,7 +238,7 @@ point to <tt/cx320p1.tgi (cx320p1_tgi)/.
<descrip>
<tag><tt/cx320p1.tgi (cx320p1_tgi)/</tag>
This driver features a resolution of 320 across and 200 down with 256 colors,
This driver features a resolution of 320 across and 240 down with 256 colors,
and a slightly adjustable palette (the order of the colors can be changed in
a way that's compatible with some of the other color drivers).
</descrip><p>
@ -248,10 +256,10 @@ point to <tt/cx16-std.joy (cx16_std_joy)/.
<descrip>
<tag><tt/cx16-std.joy (cx16_std_joy)/</tag>
Supports up to two NES (and SNES) controllers connected to the joystick ports
of the CX16. It reads the four directions, and the <bf/A/, <bf/B/,
<bf/Select/, and <bf/Start/ buttons. Buttons <bf/A/ and <bf/B/ are
the first and second fire buttons.
Supports the keyboard emulation of a controller and up to four SNES (and NES)
controllers connected to the joystick ports of the CX16. It reads the four
directions, and the <bf/A/, <bf/B/, <bf/Select/, and <bf/Start/ buttons.
Buttons <bf/A/ and <bf/B/ are the first and second fire buttons.
</descrip><p>

37
include/cx16.h
View File

@ -3,7 +3,7 @@
/* cx16.h */
/* */
/* CX16 system-specific definitions */
/* For prerelease 38 */
/* For prerelease 39 */
/* */
/* */
/* This software is provided "as-is", without any expressed or implied */
@ -172,11 +172,16 @@ enum {
};
/* Video modes for videomode() */
#define VIDEOMODE_40x30 0x00
#define VIDEOMODE_80x60 0x02
#define VIDEOMODE_40COL VIDEOMODE_40x30
#define VIDEOMODE_80x60 0x00
#define VIDEOMODE_80x30 0x01
#define VIDEOMODE_40x60 0x02
#define VIDEOMODE_40x30 0x03
#define VIDEOMODE_40x15 0x04
#define VIDEOMODE_20x30 0x05
#define VIDEOMODE_20x15 0x06
#define VIDEOMODE_80COL VIDEOMODE_80x60
#define VIDEOMODE_320x200 0x80
#define VIDEOMODE_40COL VIDEOMODE_40x30
#define VIDEOMODE_320x240 0x80
#define VIDEOMODE_SWAP (-1)
/* VERA's address increment/decrement numbers */
@ -224,6 +229,13 @@ enum {
/* Define hardware. */
#define RAM_BANK (*(unsigned char *)0x00)
#define ROM_BANK (*(unsigned char *)0x01)
#include <_6522.h>
#define VIA1 (*(volatile struct __6522 *)0x9F00)
#define VIA2 (*(volatile struct __6522 *)0x9F10)
/* A structure with the Video Enhanced Retro Adapter's external registers */
struct __vera {
unsigned short address; /* Address for data ports */
@ -274,12 +286,15 @@ struct __vera {
};
#define VERA (*(volatile struct __vera *)0x9F20)
#include <_6522.h>
#define VIA1 (*(volatile struct __6522 *)0x9F60)
#define VIA2 (*(volatile struct __6522 *)0x9F70)
#define RAM_BANK (VIA1.pra)
#define ROM_BANK (VIA1.prb)
/* Audio chip */
struct __ym2151 {
union {
unsigned char reg; /* Register number for data */
unsigned char status; /* Busy flag */
};
unsigned char data;
};
#define YM2151 (*(volatile struct __ym2151 *)0x9F40)
/* A structure with the x16emu's settings registers */
struct __emul {

7
libsrc/cx16/cgetc.s
View File

@ -1,5 +1,5 @@
;
; 2019-12-22, Greg King
; 2022-03-29, Greg King
;
; char cgetc (void);
; /* Return a character from the keyboard. */
@ -13,6 +13,8 @@
.macpack generic
screen_addr := $1B000 ; VRAM address of text screen
_cgetc: jsr _kbhit
bnz L3 ; Jump if there are already chars waiting
@ -57,8 +59,9 @@ setcursor:
stz VERA::CTRL ; Use port 0
lda CURS_Y
add #<(>screen_addr)
sta VERA::ADDR+1 ; Set row number
lda #VERA::INC1 ; Increment address by one
lda #VERA::INC1 | ^screen_addr ; Increment address by one
sta VERA::ADDR+2
lda CURS_X ; Get character column
asl a

9
libsrc/cx16/cpeekc.s
View File

@ -1,6 +1,6 @@
;
; 2016-02-28, Groepaz
; 2020-04-29, Greg King
; 2022-03-29, Greg King
;
; char cpeekc (void);
; /* Return the character from the current cursor position. */
@ -9,13 +9,18 @@
.export _cpeekc
.include "cx16.inc"
.macpack generic
screen_addr := $1B000 ; VRAM address of text screen
_cpeekc:
stz VERA::CTRL ; use port 0
lda CURS_Y
add #<(>screen_addr)
sta VERA::ADDR+1 ; set row number
stz VERA::ADDR+2
lda #^screen_addr
sta VERA::ADDR+2
lda CURS_X ; get character column
asl a ; each character has two bytes
sta VERA::ADDR

9
libsrc/cx16/cpeekcolor.s
View File

@ -1,5 +1,5 @@
;
; 2020-04-30, Greg King
; 2022-03-29, Greg King
;
; unsigned char cpeekcolor (void);
; /* Return the colors from the current cursor position. */
@ -8,8 +8,11 @@
.export _cpeekcolor
.include "cx16.inc"
.macpack generic
screen_addr := $1B000 ; VRAM address of text screen
_cpeekcolor:
php
lda CURS_FLAG ; is the cursor currently off?
@ -22,8 +25,10 @@ _cpeekcolor:
@L1: stz VERA::CTRL ; use port 0
lda CURS_Y
add #<(>screen_addr)
sta VERA::ADDR+1 ; set row number
stz VERA::ADDR+2
lda #^screen_addr
sta VERA::ADDR+2
lda CURS_X ; get character column
sec ; color attribute is second byte
rol a

9
libsrc/cx16/cpeekrevers.s
View File

@ -1,6 +1,6 @@
;
; 2016-02-28, Groepaz
; 2020-04-30, Greg King
; 2022-03-29, Greg King
;
; unsigned char cpeekrevers (void);
; /* Return the reverse attribute from the current cursor position.
@ -11,8 +11,11 @@
.export _cpeekrevers
.include "cx16.inc"
.macpack generic
screen_addr := $1B000 ; VRAM address of text screen
_cpeekrevers:
php
lda CURS_FLAG ; is the cursor currently off?
@ -25,8 +28,10 @@ _cpeekrevers:
@L1: stz VERA::CTRL ; use port 0
lda CURS_Y
add #<(>screen_addr)
sta VERA::ADDR+1 ; set row number
stz VERA::ADDR+2
lda #^screen_addr
sta VERA::ADDR+2
lda CURS_X ; get character column
asl a ; each character has two bytes
sta VERA::ADDR

10
libsrc/cx16/cputc.s
View File

@ -11,8 +11,11 @@
.import gotoxy, PLOT
.include "cx16.inc"
.macpack generic
screen_addr := $1B000 ; VRAM address of text screen
; Move to a cursor position, then print a character.
_cputcxy:
@ -79,16 +82,17 @@ putchar:
tax
stz VERA::CTRL ; Use port 0
lda CURS_Y
add #<(>screen_addr)
sta VERA::ADDR+1 ; Set row number
lda #VERA::INC1 ; Address increments by one
lda #VERA::INC1 | ^screen_addr ; Address increments by one
sta VERA::ADDR+2
ldy CURS_X ; Get character column into .Y
tya
asl a ; Each character has two bytes
sta VERA::ADDR
stx VERA::DATA0
stx VERA::DATA0 ; Put the character
lda CHARCOLOR
sta VERA::DATA0
sta VERA::DATA0 ; Put its colors
rts

43
libsrc/cx16/crt0.s
View File

@ -1,5 +1,5 @@
;
; Start-up code for cc65 (CX16 r35 version)
; Start-up code for cc65 (CX16 r39 version)
;
.export _exit
@ -20,7 +20,7 @@
.segment "STARTUP"
Start: tsx
stx spsave ; Save the system stack ptr
stx spsave ; Save the system stack ptr.
; Save space by putting some of the start-up code in the ONCE segment
; which will be re-used by the BSS segment, the heap, and the C stack.
@ -46,26 +46,14 @@ _exit:
jsr donelib
.if 0 ; (We don't need to preserve zero-page space for cc65's variables.)
; Copy back the zero-page stuff.
ldx #zpspace-1
L2: lda zpsave,x
sta sp,x
dex
bpl L2
.endif
; Restore the system stuff.
ldx spsave
txs ; Restore stack pointer
ldx ramsave
stx VIA1::PRA ; Restore former RAM bank
lda VIA1::PRB
and #<~$07
ora #$04
sta VIA1::PRB ; Change back to BASIC ROM
stx RAM_BANK ; Restore former RAM bank
lda #$04
sta ROM_BANK ; Change back to BASIC ROM
; Back to BASIC.
@ -79,26 +67,14 @@ L2: lda zpsave,x
init:
; Change from BASIC's ROM to Kernal's ROM.
lda VIA1::PRB
and #<~$07
sta VIA1::PRB
stz ROM_BANK
; Change to the second RAM bank.
lda VIA1::PRA
lda RAM_BANK
sta ramsave ; Save the current RAM bank number
lda #$01
sta VIA1::PRA
.if 0 ; (We don't need to preserve zero-page space for cc65's variables.)
; Save the zero-page locations that we need.
ldx #zpspace-1
L1: lda sp,x
sta zpsave,x
dex
bpl L1
.endif
sta RAM_BANK
; Set up the stack.
@ -125,6 +101,3 @@ L1: lda sp,x
ramsave:
.res 1
spsave: .res 1
.if 0
zpsave: .res zpspace
.endif

13
libsrc/cx16/joy/cx16-std.s
View File

@ -2,7 +2,7 @@
; Standard joystick driver for the CX16.
; May be installed multiple times when statically linked to an application.
;
; 2019-12-24, Greg King
; 2021-04-07, Greg King
;
.include "joy-kernel.inc"
@ -41,7 +41,7 @@
; ------------------------------------------------------------------------
; Constant
JOY_COUNT = 2 ; Number of joysticks we support
JOY_COUNT = $05 ; Number of joysticks we support
; ------------------------------------------------------------------------
; Data.
@ -51,8 +51,7 @@ JOY_COUNT = 2 ; Number of joysticks we support
; ------------------------------------------------------------------------
; INSTALL routine -- is called after the driver is loaded into memory.
; If possible, check if the hardware is present, and determine the amount
; of memory available.
; If possible, check if the hardware is present.
; Must return a JOY_ERR_xx code in .XA .
INSTALL:
@ -77,8 +76,10 @@ COUNT: lda #<JOY_COUNT
; ------------------------------------------------------------------------
; READ: Read a particular joystick passed in .A .
READ: and #%00000001
jsr JOYSTICK_GET
READ: cmp #JOY_COUNT
blt :+
lda #$00
: jsr JOYSTICK_GET
sta tmp1
txa
bit #%00001110 ; Is it NES or SNES controller?

11
libsrc/cx16/kbhit.s
View File

@ -1,5 +1,5 @@
;
; 2020-01-08, Greg King
; 2022-03-28, Greg King
;
; unsigned char kbhit (void);
; /* Returns non-zero (true) if a typed character is waiting. */
@ -7,14 +7,11 @@
.export _kbhit
.include "cx16.inc"
.import KBDBUF_PEEK
.proc _kbhit
ldy VIA1::PRA ; (KEY_COUNT is in RAM bank 0)
stz VIA1::PRA
lda KEY_COUNT ; Get number of characters
sty VIA1::PRA
tax ; High byte of return (only its zero/nonzero ...
jsr KBDBUF_PEEK
txa ; Low byte of return (only its zero/nonzero ...
rts ; ... state matters)
.endproc

11
libsrc/cx16/kernal.s
View File

@ -1,13 +1,18 @@
;
; 2020-04-27, Greg King
; 2022-03-28, Greg King
;
; CX16 Kernal functions
;
.include "cbm_kernal.inc"
.export KBDBUF_PEEK
.export KBDBUF_GET_MODIFIERS
.export KBDBUF_PUT
.export I2C_READ_BYTE
.export I2C_WRITE_BYTE
.export CX_MONITOR
.export ENTROPY_GET
.export KEYBRD_BUF_PUT
.export CONSOLE_SET_PAGE_MSG
.export CONSOLE_PUT_IMAGE
.export CONSOLE_INIT
@ -50,7 +55,7 @@
.export CLOCK_GET_DATE_TIME
.export JOYSTICK_SCAN
.export JOYSTICK_GET
.export SCREEN_SET_MODE
.export SCREEN_MODE
.export SCREEN_SET_CHARSET
.export MOUSE_CONFIG
.export MOUSE_GET

5
libsrc/cx16/mou/cx16-std.s
View File

@ -1,7 +1,7 @@
;
; Driver for the Commander X16 Kernal's mouse driver.
;
; 2019-12-25, Greg King
; 2022-03-28, Greg King
;
.include "zeropage.inc"
@ -118,7 +118,8 @@ INSTALL:
dex
bpl @L1
ldx #$00 ; Don't change sprite's scale
sec ; Get screen geometry
jsr SCREEN_MODE
lda #$01 ; Create sprite
jsr MOUSE_CONFIG

31
libsrc/cx16/tgi/cx320p1.s
View File

@ -1,8 +1,8 @@
;
; Graphics driver for the 320 pixels across, 200 pixels down, 256 colors mode
; Graphics driver for the 320 pixels across, 240 pixels down, 256 colors mode
; on the Commander X16
;
; 2020-07-02, Greg King <gregdk@users.sf.net>
; 2022-03-30, Greg King <gregdk@users.sf.net>
;
.include "zeropage.inc"
@ -39,7 +39,7 @@
.byte TGI_API_VERSION ; TGI API version number
.addr $0000 ; Library reference
.word 320 ; X resolution
.word 200 ; Y resolution
.word 240 ; Y resolution
.byte <$0100 ; Number of drawing colors
.byte 1 ; Number of screens available
.byte 8 ; System font X size
@ -100,7 +100,7 @@ palette: .res $0100
bcolor := palette + 0 ; Background color
color: .res 1 ; Stroke and fill index
mode: .res 1 ; Old text mode
text_mode: .res 1 ; Old text mode
.data
@ -152,13 +152,15 @@ INIT: stz error ; #TGI_ERR_OK
; Save the current text mode.
lda SCREEN_MODE
sta mode
sec
jsr SCREEN_MODE
sta text_mode
; Switch into (320 x 200 x 256) graphics mode.
; Switch into (320 x 240 x 256) graphics mode.
lda #GRAPH320
jmp SCREEN_SET_MODE
clc
jmp SCREEN_MODE
; ------------------------------------------------------------------------
; DONE: Will be called to switch the graphics device back into text mode.
@ -168,16 +170,9 @@ INIT: stz error ; #TGI_ERR_OK
; Must set an error code: NO
DONE:
; Work around a prerelease 37 Kernal bug.
; VERA (graphics) layer 0 isn't disabled by SCREEN_SET_MODE.
stz VERA::CTRL
lda VERA::DISP::VIDEO
and #<~VERA::DISP::ENABLE::LAYER0
sta VERA::DISP::VIDEO
lda mode
jmp SCREEN_SET_MODE
lda text_mode
clc
jmp SCREEN_MODE
; ------------------------------------------------------------------------
; GETERROR: Return the error code in .A, and clear it.

36
libsrc/cx16/videomode.s
View File

@ -1,10 +1,15 @@
;
; 2020-01-06, Greg King
; 2022-03-28, Greg King
;
; /* Video mode defines */
; #define VIDEOMODE_40x30 0x00
; #define VIDEOMODE_80x60 0x02
; #define VIDEOMODE_320x200 0x80
; #define VIDEOMODE_80x60 0x00
; #define VIDEOMODE_80x30 0x01
; #define VIDEOMODE_40x60 0x02
; #define VIDEOMODE_40x30 0x03
; #define VIDEOMODE_40x15 0x04
; #define VIDEOMODE_20x30 0x05
; #define VIDEOMODE_20x15 0x06
; #define VIDEOMODE_320x240 0x80
; #define VIDEOMODE_SWAP (-1)
;
; signed char __fastcall__ videomode (signed char Mode);
@ -16,25 +21,26 @@
.export _videomode
.import SCREEN_SET_MODE
.include "cx16.inc"
.import SCREEN_MODE
.proc _videomode
ldx SCREEN_MODE ; Get old mode
phx
jsr SCREEN_SET_MODE
sec ; Get old mode
pha
jsr SCREEN_MODE
plx
pha ; Save old mode
txa
clc ; Set new mode
jsr SCREEN_MODE
pla ; Get back old mode
ldx #>$0000 ; Clear high byte
bcs @L1
rts
bcc @L1
; The new mode is invalid. Go back to the old one. Return -1.
; The new mode is invalid. Return -1.
@L1: sta SCREEN_MODE
dex
txa
rts
@L1: rts
.endproc

8
libsrc/cx16/waitvsync.s
View File

@ -1,5 +1,5 @@
;
; 2020-01-08, Greg King
; 2021-04-01, Greg King
;
; void waitvsync (void);
; /* Wait for the start of the next video field. */
@ -12,10 +12,10 @@
.include "cx16.inc"
_waitvsync:
ldx VIA1::PRA ; (TIMER is in RAM bank 0)
stz VIA1::PRA
ldx RAM_BANK ; (TIMER is in RAM bank 0)
stz RAM_BANK
lda TIMER + 2
: cmp TIMER + 2
beq :- ; Wait for next jiffy
stx VIA1::PRA
stx RAM_BANK
rts