Video Port

NIOS II For Quartus Prime

9.5 VideoOut #include "address_map_nios2.h"

/* function prototypes */ void video_text(int, int, char *); void video_box(int, int, int, int, short); int resample_rgb(int, int); int get_data_bits(int);
#define STANDARD_X 320 #define STANDARD_Y 240 #define INTEL_BLUE 0x0071C5 /* global variables */ int screen_x; int screen_y; int res_offset; int col_offset;
/* This program demonstrates use of the video in the computer system. * Draws a blue box on the video display, and places a text string inside the * box ******************************************************************************/ int main(void) { volatile int * video_resolution = (int *)(PIXEL_BUF_CTRL_BASE + 0x8); screen_x = *video_resolution & 0xFFFF; screen_y = (*video_resolution >> 16) & 0xFFFF;
volatile int * rgb_status = (int *)(RGB_RESAMPLER_BASE); int db = get_data_bits(*rgb_status & 0x3F);
/* check if resolution is smaller than the standard 320 x 240 */ res_offset = (screen_x == 160) ? 1 : 0;
/* check if number of data bits is less than the standard 16-bits */ col_offset = (db == 8) ? 1 : 0;
/* create a message to be displayed on the video and LCD displays */ char text_top_row[40] = "Intel FPGA\0"; char text_bottom_row[40] = "Computer Systems\0";
/* update color */ short background_color = resample_rgb(db, INTEL_BLUE);
video_text(35, 29, text_top_row); video_text(32, 30, text_bottom_row); video_box(0, 0, STANDARD_X, STANDARD_Y, 0); // clear the screen video_box(31 * 4, 28 * 4, 49 * 4 - 1, 32 * 4 - 1, background_color);
}

/* Subroutine to send a string of text to the video monitor */ void video_text(int x, int y, char * text_ptr) { int offset; volatile char * character_buffer = (char *)FPGA_CHAR_BASE; // video character buffer
/* assume that the text string fits on one line */ offset = (y << 7) + x; while (*(text_ptr)) { *(character_buffer + offset) = *(text_ptr); // write to the character buffer ++text_ptr; ++offset; }
}
/* Draw a filled rectangle on the video monitor * Takes in points assuming 320x240 resolution and adjusts based on differences * in resolution and color bits. ******************************************************************************/ void video_box(int x1, int y1, int x2, int y2, short pixel_color) { int pixel_buf_ptr = *(int *)PIXEL_BUF_CTRL_BASE; int pixel_ptr, row, col; int x_factor = 0x1 << (res_offset + col_offset); int y_factor = 0x1 << (res_offset); x1 = x1 / x_factor; x2 = x2 / x_factor; y1 = y1 / y_factor; y2 = y2 / y_factor;
/* assume that the box coordinates are valid */ for (row = y1; row <= y2; row++) for (col = x1; col <= x2; ++col) { pixel_ptr = pixel_buf_ptr + (row << (10 - res_offset - col_offset)) + (col << 1); *(short *)pixel_ptr = pixel_color; // set pixel color }
}
/* Resamples 24-bit color to 16-bit or 8-bit color */ int resample_rgb(int num_bits, int color) { if (num_bits == 8) { color = (((color >> 16) & 0x000000E0) | ((color >> 11) & 0x0000001C) | ((color >> 6) & 0x00000003)); color = (color << 8) | color; } else if (num_bits == 16) {

color = (((color >> 8) & 0x0000F800) | ((color >> 5) & 0x000007E0) | ((color >> 3) & 0x0000001F));
} return color; 
}

/* Finds the number of data bits from the mode */ int get_data_bits(int mode) { switch (mode) { case 0x0: return 1; case 0x7: return 8; case 0x11: return 8; case 0x12: return 9; case 0x14: return 16; case 0x17: return 24; case 0x19: return 30; case 0x31: return 8; case 0x32: return 12; case 0x33: return 16; case 0x37: return 32; case 0x39: return 40; } } Listing 15. An example of code that uses the video-out por