6502/CLK
1
0
Fork 0
mirror of https://github.com/TomHarte/CLK.git synced 2024-12-23 20:29:42 +00:00
Code Issues Projects Releases Wiki Activity

Implement most of CGA text mode.

Browse Source
This commit is contained in:
Thomas Harte 2023-12-06 09:42:22 -05:00
parent 2216fc37a1
commit 561e50a24d
1 changed files with 27 additions and 36 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

63
Machines/PCCompatible/CGA.hpp
View File

@ -143,54 +143,45 @@ class CGA {
}
if(pixels) {
static constexpr uint8_t high_intensity = 0x0d;
static constexpr uint8_t low_intensity = 0x09;
static constexpr uint8_t off = 0x00;
if(state.cursor) {
pixel_pointer[0] = pixel_pointer[1] = pixel_pointer[2] = pixel_pointer[3] =
pixel_pointer[4] = pixel_pointer[5] = pixel_pointer[6] = pixel_pointer[7] =
pixel_pointer[8] = low_intensity;
pixel_pointer[8] = 0x3f; // i.e. white.
} else {
const uint8_t attributes = ram[((state.refresh_address << 1) + 1) & 0xfff];
const uint8_t glyph = ram[((state.refresh_address << 1) + 0) & 0xfff];
uint8_t row = font[(glyph * 14) + state.row_address];
const uint8_t row = font[(glyph * 8) + state.row_address];
const uint8_t intensity = (attributes & 0x08) ? high_intensity : low_intensity;
uint8_t blank = off;
uint8_t colours[2] = {
uint8_t(((attributes & 0x40) >> 1) | ((attributes & 0x20) >> 2) | ((attributes & 0x10) >> 3)),
uint8_t(((attributes & 0x04) << 3) | ((attributes & 0x02) << 2) | ((attributes & 0x01) << 1)),
};
// Handle irregular attributes.
// Cf. http://www.seasip.info/VintagePC/mda.html#memmap
switch(attributes) {
case 0x00: case 0x08: case 0x80: case 0x88:
row = 0;
break;
case 0x70: case 0x78: case 0xf0: case 0xf8:
row ^= 0xff;
blank = intensity;
break;
// Apply foreground intensity.
if(attributes & 0x08) {
colours[1] |= colours[1] >> 1;
}
// Apply blink if enabled.
if((control_ & 0x20) && (attributes & 0x80) && (state.field_count & 16)) {
row ^= 0xff;
blank = (blank == off) ? intensity : off;
}
if(((attributes & 7) == 1) && state.row_address == 13) {
// Draw as underline.
std::fill(pixel_pointer, pixel_pointer + 8, intensity);
// Apply blink or background intensity.
if(control_ & 0x20) {
if((attributes & 0x80) && (state.field_count & 16)) {
std::swap(colours[0], colours[1]);
}
} else {
// Draw according to ROM contents, possibly duplicating final column.
pixel_pointer[0] = (row & 0x80) ? intensity : off;
pixel_pointer[1] = (row & 0x40) ? intensity : off;
pixel_pointer[2] = (row & 0x20) ? intensity : off;
pixel_pointer[3] = (row & 0x10) ? intensity : off;
pixel_pointer[4] = (row & 0x08) ? intensity : off;
pixel_pointer[5] = (row & 0x04) ? intensity : off;
pixel_pointer[6] = (row & 0x02) ? intensity : off;
pixel_pointer[7] = (row & 0x01) ? intensity : off;
if(attributes & 0x80) {
colours[0] |= colours[0] >> 1;
}
}
// Draw according to ROM contents.
pixel_pointer[0] = (row & 0x80) ? colours[1] : colours[0];
pixel_pointer[1] = (row & 0x40) ? colours[1] : colours[0];
pixel_pointer[2] = (row & 0x20) ? colours[1] : colours[0];
pixel_pointer[3] = (row & 0x10) ? colours[1] : colours[0];
pixel_pointer[4] = (row & 0x08) ? colours[1] : colours[0];
pixel_pointer[5] = (row & 0x04) ? colours[1] : colours[0];
pixel_pointer[6] = (row & 0x02) ? colours[1] : colours[0];
pixel_pointer[7] = (row & 0x01) ? colours[1] : colours[0];
}
pixel_pointer += 8;
}