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84 lines
1.9 KiB
84 lines
1.9 KiB
#ifndef KERNEL_VGA_H
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#define KERNEL_VGA_H
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// Base memory address for MM VGA
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#define VGA_ADDRESS 0xb8000
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// Max character cell dimensions
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#define VGA_MAX_ROWS 25
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#define VGA_MAX_COLS 80
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// Default color scheme
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#define VGA_WHITE_ON_BLACK 0x0f
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// Screen device I/O ports
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#define REG_VGA_CTL 0x3d4
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#define REG_VGA_DATA 0x3d5
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class VGA {
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protected:
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/**
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* Given a column and row of a VGA character cell, compute the memory
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* offset from the beginning of the VGA video memory of its char and
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* attr bytes.
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* @param col
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* @param row
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* @return the computed offset
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*/
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int getOffset(int col, int row);
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int getOffsetRow(int offset);
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int getOffsetCol(int offset);
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/**
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* Get the memory offset of the character cell where the cursor is.
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*
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* 1. Ask for the high-byte of the offset (data 14)
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* 2. Ask for the low-byte (data 15)
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*
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* @return
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*/
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int getCursorOffset();
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/**
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* Given a VGA memory offset, set the cursor to that offset's character cell.
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* @param offset
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*/
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void setCursorOffset(int offset);
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/**
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* Print a character to the specified position.
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*
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* If col/row are negative, print to the current cursor position.
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* If attribute_byte is 0, default white on black.
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*
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* @param character
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* @param col
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* @param row
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* @param attribute_byte
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*/
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int printChar(char character, int col, int row, char attrs);
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int adjustScrolling(int offset);
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/**
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* Scrolls all the character cells up one row, replacing the top
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* row and creating a new empty row on the bottom.
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*/
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void advanceScrolling();
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public:
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/**
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* Resets all video memory characters to empty space and all formatting
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* to the default white on black. Then, reset the cursor to the first cell.
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*/
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void clearScreen();
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void printAt(char* string, int col, int row);
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void print(char* string);
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};
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#endif //KERNEL_VGA_H
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