94 lines
2.2 KiB
C
94 lines
2.2 KiB
C
#include "vga.h"
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#include "ports.h"
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#define vgaWidth 80
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#define vgaHeight 25
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#define vgaBuffer 0xB8000
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static volatile uint16* const screen = (volatile uint16*)vgaBuffer;
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static uint32 cursorRow;
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static uint32 cursorColumn;
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static uint8 currentColor;
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static uint16 makeCell(char c, uint8 color)
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{
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return (uint16)c | ((uint16)color << 8);
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}
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static void updateHardwareCursor(void)
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{
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uint16 position = (uint16)(cursorRow * vgaWidth + cursorColumn);
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outb(0x3D4, 0x0F);
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outb(0x3D5, (uint8)(position & 0xFF));
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outb(0x3D4, 0x0E);
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outb(0x3D5, (uint8)((position >> 8) & 0xFF));
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}
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void vgaSetColor(VgaColor foreground, VgaColor background)
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{
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currentColor = (uint8)foreground | (uint8)(background << 4);
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}
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void vgaClear(void)
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{
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for (uint32 y = 0; y < vgaHeight; y++) {
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for (uint32 x = 0; x < vgaWidth; x++)
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screen[y * vgaWidth + x] = makeCell(' ', currentColor);
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}
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cursorRow = 0;
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cursorColumn = 0;
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updateHardwareCursor();
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}
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void vgaInit(void)
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{
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currentColor = (uint8)vgaLightGrey | (uint8)(vgaBlack << 4);
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vgaClear();
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}
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static void scroll(void)
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{
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for (uint32 y = 1; y < vgaHeight; y++) {
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for (uint32 x = 0; x < vgaWidth; x++)
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screen[(y - 1) * vgaWidth + x] = screen[y * vgaWidth + x];
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}
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for (uint32 x = 0; x < vgaWidth; x++)
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screen[(vgaHeight - 1) * vgaWidth + x] = makeCell(' ', currentColor);
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cursorRow = vgaHeight - 1;
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}
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void vgaPutChar(char c)
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{
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if (c == '\n') {
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cursorColumn = 0;
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cursorRow++;
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} else if (c == '\r') {
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cursorColumn = 0;
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} else if (c == '\b') {
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if (cursorColumn > 0) {
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cursorColumn--;
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screen[cursorRow * vgaWidth + cursorColumn] = makeCell(' ', currentColor);
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}
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} else if (c == '\t') {
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cursorColumn = (cursorColumn + 4) & ~3u;
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} else {
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screen[cursorRow * vgaWidth + cursorColumn] = makeCell(c, currentColor);
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cursorColumn++;
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}
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if (cursorColumn >= vgaWidth) {
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cursorColumn = 0;
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cursorRow++;
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}
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if (cursorRow >= vgaHeight)
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scroll();
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updateHardwareCursor();
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}
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void vgaWriteString(const char* str)
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{
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while (*str)
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vgaPutChar(*str++);
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}
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