I was working with Jeff Stone over on Discord, and he was asking about why his code crashes. The intention is to write a simple program that reports the status of the two joysticks.
I have found that the following code works perfectly when I do *NOT* define DISABLE_VDP. However if I do DISABLE_VDP, the program crashes and the system warm boots. The crash is not immediate. It works for a few joystick state changes before crashing.
I don't know if this is only a CP/M thing or not.
It feels to me like there is some kind of conflict between the VDP interrupt and the Keyboard interrupt? The crash never happens when VDP is enabled.
Code: Select all
#define DISABLE_HCCA_RX_INT
#define DISABLE_CURSOR
// #define DISABLE_VDP // If you dssable VDP in NABU-LIB, the program crashes and CP/M warm boots.
// #define DISABLE_KEYBOARD_INT // The NABU-LIB functions for the joystick depend on the KBD interrupts.
#include <stdio.h>
#include "NABU-LIB.h"
uint8_t status0, lastStatus0, status1, lastStatus1 = 0; //Record the status of the joystick in these vars.
uint8_t main(void) {
/*The NABU Keyboard Controller only reports changes to the joystick.
* NABU-LIB tracks these in a global variable which allows us to poll the
* Joystick. It's possible that Marduk and Ishkur CP/M do not manage the
* joystick input in the same way as DJ's CloudCP/M BIOS.
*
* To do this without NABU-LIB, you will need to write code to handle the
* Keyboard interrupt yourself.
*/
initNABULib();
// Here I am basically tracking the status of the joystick as reported by
// NABU-LIB and printing a message to the screen if it changes.
printf("Joystick Test Program:\n");
printf("Move the Joystick and press the button.\n");
printf("Hit Q to quit.\n\n");
while(1) {
status0 = getJoyStatus(0);
if (status0 != lastStatus0) {
if(status0 & Joy_Left) {
printf("J0 - LEFT ... ");
} else if (status0 & Joy_Right) {
printf("J0 - RIGHT ... ");
} else if (status0 & Joy_Up) {
printf("J0 - UP ... ");
} else if (status0 & Joy_Down) {
printf("J0 - DOWN ... ");
} else if (status0 & Joy_Button) {
printf("J0 - BUTTON ... ");
} else {
printf("J0 - RESET\n");
}
lastStatus0 = status0;
}
status1 = getJoyStatus(1);
if (status1 != lastStatus1) {
if(status1 & Joy_Left) {
printf("J0 - LEFT\n");
} else if (status1 & Joy_Right) {
printf("J0 - RIGHT\n");
} else if (status1 & Joy_Up) {
printf("J0 - UP\n");
} else if (status1 & Joy_Down) {
printf("J0 - DOWN\n");
} else if (status1 & Joy_Button) {
printf("J0 - BUTTON\n");
} else {
printf("J0 - RESET");
}
lastStatus1 = status1;
}
if (isKeyPressed()) {
uint8_t key = getChar();
if (key == 'q' || key == 'Q') {
printf("Exiting...\n");
break;
}
}
}
return 0;
}
