16 bits

Simple sample to show you how to write a pixel, and how to do double buffering.

Using library

GP2X minimal library by rlyeh, 2005

License

  • Free for non-commercial projects (it would be nice receiving a mail from you).  Other cases, ask me first.
  • GamePark Holdings is not allowed to use this library and/or use parts from it.

Source code

#include "minimal.h"

int main(int argc, char *argv[])
{
gp2x_init(1000, 16, 11025,16,1,60, 1);

while(1)
{
unsigned long pad=gp2x_joystick_read();
unsigned short color;

if(pad & GP2X_VOL_DOWN) if(pad & GP2X_START) exit(0);

if(pad & GP2X_A) color=gp2x_video_RGB_color16(255,0,0); //red
else color=gp2x_video_RGB_color16(255,255,255); //white

gp2x_video_RGB[0].screen16[160+120*320]=color;

gp2x_video_RGB_flip(0);
}
}

void gp2x_sound_frame(void *blah, void *buff, int samples) { }

Explanation

  • Our gp2x_init line inits the whole library.  We set 1000 ticks per second, 16 bits video mode, 11025/16bits/stereo/60Hz sound mode, and solid font.
  • Our gp2x_joystick_read line reads the joystick.  It is used to act properly to different button combinations.
  • Our gp2x_video_RGB_color16 line sets color variable to a determinated color.
  • Our gp2x_video_RGB [0].screen16 line updates the pixel at the middle of screen (160,120) with our color.
  • Our gp2x_video_RGB_flip line updates the screen and our gp2x_video_RGB [0].screen16 pointer for next frame.
  • Our gp2x_sound_frame line fills our sound buffer.  Note that this function will not generate any sound since we have written a void function.

C Compilation

arm-linux-gcc minimal.c 16bits.c -static -lpthread -lm

C++ Compilation

arm-linux-g++ minimal.c 16bits.c -static -lpthread -lm

Output

  • this program puts a pixel at center of screen and does double buffering (pressing A changes the color).
  • press volume down and start buttons to exit.
void gp2x_init(int ticks_per_second,
int bpp,
int rate,
int bits,
int stereo,
int Hz,
int solid_font)
This function sets up the whole library.
unsigned long gp2x_joystick_read(void)
This function returns the active GP2X joystick values.
unsigned short gp2x_video_RGB_color16(int R,
int G,
int B)
This function returns the 16bits color for a given triad of R,G,B components.
gp2x_video_layer gp2x_video_RGB[1]
This struct allows you to work directly with RGB video layer.
void gp2x_video_RGB_flip(int layer)
This function flips video buffers.
extern void gp2x_sound_frame(void *blah,
void *buffer,
int samples)
This function is automatically called by the library, and expects a sound buffer to be filled in.