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