I’ve been doing some Dreamcast homebrew this weekend, using the great KallistiOS as well as dcload-ip. Together they make for a great development environment, and the Dreamcast itself is the easiest console I’ve ever worked with to homebrew.

This is an example I put together to show how to poll the controller for button presses, and use it to update the VMU. It’s really just what I’ve learned so far about KOS.

Technical Stuff

This example is a modified lcd.c from the KallistiOS examples/ folder. It uses the maple API to poll for that status, using maple_dev_status(), which returns a struct. This is just added as part of the main loop logic. The status struct’s button member is checked against the defined bit values for the buttons we’re interested in.

The rest of the VMU code from lcd.c is used to animate a breakout-style paddle that moves to the left and right. Start quits the program.

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#include <dc/vmu_fb.h>
#include <kos.h>

#include <stdint.h>

static const char paddle[] = {
  0b11111111,
};

static vmufb_t vmufb;

KOS_INIT_FLAGS(INIT_DEFAULT | INIT_MALLOCSTATS);

/* Your program's main entry point */
int main(int argc, char **argv) {
    unsigned int x, y;
    maple_device_t *vmu;

    cont_btn_callback(0, CONT_START,
                      (cont_btn_callback_t)arch_exit);

    // Controller status
    maple_device_t *device = maple_enum_dev(0, 0);

    x = 20;
    y = 30;

    // Main Loop
    while(1==1) {
      cont_state_t *status = maple_dev_status(device);
      if(status->buttons & CONT_DPAD_LEFT) {
        if(x > 0) {
          x -= 1;
        }
      } else if(status->buttons & CONT_DPAD_RIGHT) {
        if(x < 40) {
          x += 1;
        }
      }

      vmufb_clear(&vmufb);

      vmufb_paint_area(&vmufb, x, y, 8, 1, paddle);

      vmu = maple_enum_type(0, MAPLE_FUNC_LCD);
      vmufb_present(&vmufb, vmu);

    }

    return 0;
}

Updated: