mirror of
https://github.com/RGBCube/serenity
synced 2025-10-23 10:42:36 +00:00
3e3de67f02
Instead of memcpy'ing the entire screen every time we press enter at the bottom, use the VGA start address register to make a "view" onto the underlying memory that moves downward as we scroll. Eventually we run out of memory and have to reset to the start of the buffer. That's when we memcpy everything. It would be cool if there was some way to get the hardware to act like a ring buffer with automatic wrapping here but I don't know how to do that.
89 lines
1.6 KiB
C++
89 lines
1.6 KiB
C++
#include "types.h"
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#include "VGA.h"
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#include "i386.h"
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#include "IO.h"
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#include "StdLib.h"
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#include "Process.h"
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static byte* vga_mem = nullptr;
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void vga_clear_row(word line)
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{
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InterruptDisabler disabler;
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word* linemem = (word*)&vga_mem[line * 160];
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for (word i = 0; i < 80; ++i) {
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linemem[i] = 0x0720;
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}
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}
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void vga_clear()
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{
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InterruptDisabler disabler;
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for (word i = 0; i < 25; ++i)
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vga_clear_row(i);
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}
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void vga_putch_at(byte row, byte column, byte ch, byte attr)
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{
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word cur = (row * 160) + (column * 2);
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vga_mem[cur] = ch;
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vga_mem[cur + 1] = attr;
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}
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word vga_get_start_address()
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{
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word value;
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IO::out8(0x3d4, 0x0d);
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value = IO::in8(0x3d5) << 8;
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IO::out8(0x3d4, 0x0c);
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value |= IO::in8(0x3d5);
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return value;
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}
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void vga_set_start_address(word value)
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{
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IO::out8(0x3d4, 0x0c);
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IO::out8(0x3d5, MSB(value));
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IO::out8(0x3d4, 0x0d);
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IO::out8(0x3d5, LSB(value));
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}
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void vga_init()
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{
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vga_mem = (byte*)0xb8000;
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for (word i = 0; i < (80 * 25); ++i) {
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vga_mem[i*2] = ' ';
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vga_mem[i*2 + 1] = 0x07;
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}
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vga_set_cursor(0);
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}
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WORD vga_get_cursor()
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{
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WORD value;
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IO::out8(0x3d4, 0x0e);
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value = IO::in8(0x3d5) << 8;
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IO::out8(0x3d4, 0x0f);
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value |= IO::in8(0x3d5);
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return value;
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}
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void vga_set_cursor(WORD value)
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{
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IO::out8(0x3d4, 0x0e);
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IO::out8(0x3d5, MSB(value));
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IO::out8(0x3d4, 0x0f);
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IO::out8(0x3d5, LSB(value));
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}
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void vga_set_cursor(BYTE row, BYTE column)
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{
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vga_set_cursor(row * 80 + column);
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}
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void vga_set_cursor(byte row, byte column, word start_address)
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{
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vga_set_cursor((start_address) + (row * 80 + column));
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}
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