49 lines
1.4 KiB
C
49 lines
1.4 KiB
C
// Driver implementation for Jank's text frame buffer
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// Buffer can display 80 columns by 25 Rows
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// Start of buffer is at (real)address 0x000B8000
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// Memory at this section is divided into 16-bit cells
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// | 15-8 | 7-4 | 0-3
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// | Asci | FG | BG
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#include "types.h"
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#include "framebuffer.h"
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// State trackers from header
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static u8* Frame_Buffer = (u8*)FRAME_BUFFER_ADDR;
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s32 Frame_Buffer_Cursor = 0x0000;
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void frame_buffer_newline() {
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while(Frame_Buffer_Cursor != (AREA*8)) {
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if((Frame_Buffer_Cursor % 160) == 0) {
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break;
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Frame_Buffer_Cursor+=160;
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}
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else {
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Frame_Buffer_Cursor+=2;
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}
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}
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}
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// Writes character to a given cell in the framebuffer
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// @cell parameter is the logical (linear)index into the buffer
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void write_cell_fb(u8 c, u8 fg, u8 bg) {
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Frame_Buffer[Frame_Buffer_Cursor] = c;
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Frame_Buffer[Frame_Buffer_Cursor+1] = (fg & 0x0f << 4) | (bg & 0x0f);
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Frame_Buffer_Cursor += 2;
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}
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void clear_fb(void) {
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for(unsigned cell=0;cell<AREA; cell+=2) {
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write_cell_fb(' ', 0x00, 0x00);
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}
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Frame_Buffer_Cursor = 0x0000;
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}
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// Takes the linear indexed position to move the cursos, if there is nothing at that position we should still have something there
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void fb_move_cursor(u16 position) {
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serialport_write_byte(FB_CMD, FB_HIGH_CMD);
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serialport_write_byte(FB_DATA, ((position >> 8) & 0x00ff) );
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serialport_write_byte(FB_CMD, FB_LOW_CMD);
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serialport_write_byte(FB_DATA, position & 0x00ff);
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}
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