analog-firmware/vga/render_hires.c
2023-04-05 23:53:21 -04:00

114 lines
4.0 KiB
C

#include <pico/stdlib.h>
#include "common/config.h"
#include "vga/hires_color_patterns.h"
#include "vga/hires_dot_patterns.h"
#include "vga/vgabuf.h"
#include "vga/render.h"
#include "vga/vgaout.h"
//#define PAGE2SEL (!(soft_switches & SOFTSW_80STORE) && (soft_switches & SOFTSW_PAGE_2))
#define PAGE2SEL ((soft_switches & (SOFTSW_80STORE | SOFTSW_PAGE_2)) == SOFTSW_PAGE_2)
static void render_hires_line(bool p2, uint line);
static inline uint hires_line_to_mem_offset(uint line) {
return ((line & 0x07) << 10) | ((line & 0x38) << 4) | (((line & 0xc0) >> 6) * 40);
}
void DELAYED_COPY_CODE(render_hires)() {
for(uint line=0; line < 192; line++) {
render_hires_line(PAGE2SEL, line);
}
}
void DELAYED_COPY_CODE(render_mixed_hires)() {
for(uint line=0; line < 160; line++) {
render_hires_line(PAGE2SEL, line);
}
for(uint line=20; line < 24; line++) {
if(soft_switches & SOFTSW_80COL) {
render_text80_line(PAGE2SEL, line);
} else {
render_text40_line(PAGE2SEL, line);
}
}
}
static void DELAYED_COPY_CODE(render_hires_line)(bool p2, uint line) {
struct vga_scanline *sl = vga_prepare_scanline();
uint sl_pos = 0;
const uint8_t *line_mem = (const uint8_t *)((p2 ? hgr_p2 : hgr_p1) + hires_line_to_mem_offset(line));
// Pad 40 pixels on the left to center horizontally
sl->data[sl_pos++] = (text_border|THEN_EXTEND_31) | ((text_border|THEN_EXTEND_7) << 16); // 16 pixels per word
// Each hires byte contains 7 pixels which may be shifted right 1/2 a pixel. That is
// represented here by 14 'dots' to precisely describe the half-pixel positioning.
//
// For each pixel, inspect a window of 8 dots around the pixel to determine the
// precise dot locations and colors.
//
// Dots would be scanned out to the CRT from MSB to LSB (left to right here):
//
// previous | next
// dots | dots
// +-------------------+--------------------------------------------------+
// dots: | 31 | 30 | 29 | 28 | 27 | 26 | 25 | 24 | 23 | ... | 14 | 13 | 12 | ...
// | | | |
// \______________|_________|______________/
// | |
// \_________/
// current
// pixel
uint32_t dots = 0;
uint oddness = 0;
uint i, j;
// Load in the first 14 dots
dots |= (uint32_t)hires_dot_patterns[line_mem[0]] << 15;
for(i=1; i < 41; i++) {
// Load in the next 14 dots
uint b = (i < 40) ? line_mem[i] : 0;
if(b & 0x80) {
// Extend the last bit from the previous byte
dots |= (dots & (1u << 15)) >> 1;
}
dots |= (uint32_t)hires_dot_patterns[b] << 1;
if((soft_switches & SOFTSW_MONOCHROME) || (mono_palette & 0x8)) {
// Consume 14 dots
for(j = 0; j < 7; j++) {
uint32_t pixeldata = (dots & 0x40000000) ? (text_fore) : (text_back);
pixeldata |= (dots & 0x20000000) ?
((text_fore) << 16) :
((text_back) << 16);
dots <<= 2;
sl->data[sl_pos] = pixeldata;
sl_pos++;
}
} else {
// Consume 14 dots
for(uint j=0; j < 7; j++) {
uint dot_pattern = oddness | ((dots >> 24) & 0xff);
sl->data[sl_pos] = hires_color_patterns[dot_pattern];
sl_pos++;
dots <<= 2;
oddness ^= 0x100;
}
}
}
// Pad 40 pixels on the right to center horizontally
sl->data[sl_pos++] = (text_border|THEN_EXTEND_31) | ((text_border|THEN_EXTEND_7) << 16); // 16 pixels per word
sl->length = sl_pos;
sl->repeat_count = 1;
vga_submit_scanline(sl);
}