analog/v2-analog-rev1/vga/render_videx.c

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#include <pico/stdlib.h>
#include "vgabuf.h"
#include "render.h"
#include "character_rom.h"
#include "vgaout.h"
static inline uint_fast8_t __time_critical_func(char_terminal_bits)(uint_fast8_t ch, uint_fast8_t glyph_line) {
uint_fast8_t bits = videx_character_rom[((uint_fast16_t)ch << 3) | glyph_line];
if(ch & 0x80) {
// normal character
return bits & 0x7f;
}
if((bits & 0x80) == 0) {
// inverse character
return bits ^ 0x7f;
} else {
// flashing character
return (bits ^ text_flasher_mask) & 0x7f;
}
}
void __time_critical_func(render_videx)() {
for(int line=0; line < 24; line++) {
render_videx_line(line);
}
}
void __time_critical_func(render_videx_line)(unsigned int line) {
const uint8_t *page = (const uint8_t *)videx_memory;
const uint8_t *line_buf = page + (line * 80);
for(uint glyph_line=0; glyph_line < 8; glyph_line++) {
struct vga_scanline *sl = vga_prepare_scanline();
uint sl_pos = 0;
// Pad 40 pixels on the left to center horizontally
sl->data[sl_pos++] = (text_border|THEN_EXTEND_7) | ((text_border|THEN_EXTEND_7) << 16); // 16 pixels per word
sl->data[sl_pos++] = (text_border|THEN_EXTEND_7) | ((text_border|THEN_EXTEND_7) << 16); // 16 pixels per word
sl->data[sl_pos++] = (text_border|THEN_EXTEND_3) | ((text_border|THEN_EXTEND_3) << 16); // 8 pixels per word
for(uint col=0; col < 80; ) {
// Grab 14 pixels from the next two characters
uint32_t bits_a = char_terminal_bits(line_buf[col], glyph_line);
col++;
uint32_t bits_b = char_terminal_bits(line_buf[col], glyph_line);
col++;
uint32_t bits = (bits_a << 7) | bits_b;
// Translate each pair of bits into a pair of pixels
for(int i=0; i < 7; i++) {
uint32_t pixeldata = (bits & 0x2000) ? (text_fore) : (text_back);
pixeldata |= (bits & 0x1000) ?
(((uint32_t)text_fore) << 16) :
(((uint32_t)text_back) << 16);
bits <<= 2;
sl->data[sl_pos] = pixeldata;
sl_pos++;
}
}
// Pad 40 pixels on the left to center horizontally
sl->data[sl_pos++] = (text_border|THEN_EXTEND_7) | ((text_border|THEN_EXTEND_7) << 16); // 16 pixels per word
sl->data[sl_pos++] = (text_border|THEN_EXTEND_7) | ((text_border|THEN_EXTEND_7) << 16); // 16 pixels per word
sl->data[sl_pos++] = (text_border|THEN_EXTEND_3) | ((text_border|THEN_EXTEND_3) << 16); // 8 pixels per word
sl->length = sl_pos;
sl->repeat_count = 1;
vga_submit_scanline(sl);
}
}