diff options
Diffstat (limited to 'arch/x86/machine/vga.c')
| -rw-r--r-- | arch/x86/machine/vga.c | 184 |
1 files changed, 184 insertions, 0 deletions
diff --git a/arch/x86/machine/vga.c b/arch/x86/machine/vga.c new file mode 100644 index 00000000..60911943 --- /dev/null +++ b/arch/x86/machine/vga.c @@ -0,0 +1,184 @@ +/* + * Copyright (c) 2010, 2012 Richard Braun. + * + * This program is free software: you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation, either version 3 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program. If not, see <http://www.gnu.org/licenses/>. + */ + +#include <kern/init.h> +#include <lib/macros.h> +#include <lib/stdint.h> +#include <lib/string.h> +#include <machine/io.h> +#include <machine/pmap.h> +#include <machine/vga.h> + +/* + * Screen dimensions. + */ +#define VGA_COLUMNS 80 +#define VGA_LINES 25 + +/* + * Text mode mapped memory and size. + */ +#define VGA_MEMORY 0xb8000 +#define VGA_MEMORY_SIZE (VGA_COLUMNS * VGA_LINES * 2) + +/* + * I/O ports. + */ +#define VGA_MISC_OUTPUT_REGISTER_READ 0x3cc +#define VGA_MISC_OUTPUT_REGISTER_WRITE 0x3c2 +#define VGA_CRTC_ADDRESS_REGISTER 0x3d4 +#define VGA_CRTC_DATA_REGISTER 0x3d5 + +/* + * CRTC registers. + */ +#define VGA_CRTC_CURSOR_LOCATION_HIGH_REGISTER 0xe +#define VGA_CRTC_CURSOR_LOCATION_LOW_REGISTER 0xf + +/* + * Foreground screen color. + */ +#define VGA_FOREGROUND_COLOR 0x7 + +/* + * Blank space 16 bits word. + */ +#define VGA_BLANK ((VGA_FOREGROUND_COLOR << 8) | ' ') + +/* + * Number of spaces to display for a tabulation. + */ +#define VGA_TABULATION_SPACES 8 + +static uint8_t *vga_memory; +static uint16_t vga_cursor; + +static uint16_t +vga_get_cursor_position(void) +{ + uint16_t tmp; + + io_write_byte(VGA_CRTC_ADDRESS_REGISTER, + VGA_CRTC_CURSOR_LOCATION_HIGH_REGISTER); + tmp = io_read_byte(VGA_CRTC_DATA_REGISTER) << 8; + io_write_byte(VGA_CRTC_ADDRESS_REGISTER, + VGA_CRTC_CURSOR_LOCATION_LOW_REGISTER); + tmp |= io_read_byte(VGA_CRTC_DATA_REGISTER); + + return tmp; +} + +static void +vga_set_cursor_position(uint16_t position) +{ + io_write_byte(VGA_CRTC_ADDRESS_REGISTER, + VGA_CRTC_CURSOR_LOCATION_HIGH_REGISTER); + io_write_byte(VGA_CRTC_DATA_REGISTER, position >> 8); + io_write_byte(VGA_CRTC_ADDRESS_REGISTER, + VGA_CRTC_CURSOR_LOCATION_LOW_REGISTER); + io_write_byte(VGA_CRTC_DATA_REGISTER, position & 0xff); +} + +static uint8_t +vga_get_cursor_column(void) +{ + return vga_cursor % VGA_COLUMNS; +} + +void __init +vga_setup(void) +{ + uint8_t misc_output_register; + unsigned long va; + + va = pmap_bootalloc(1); + pmap_kenter(va, VGA_MEMORY); + vga_memory = (uint8_t *)va; + + /* + * Check if the Input/Output Address Select bit is set. + */ + misc_output_register = io_read_byte(VGA_MISC_OUTPUT_REGISTER_READ); + + if (!(misc_output_register & 0x1)) { + /* + * Set the I/O AS bit. + */ + misc_output_register |= 0x1; + + /* + * Update the misc output register. + */ + io_write_byte(VGA_MISC_OUTPUT_REGISTER_WRITE, misc_output_register); + } + + vga_cursor = vga_get_cursor_position(); +} + +static void +vga_scroll_lines(void) +{ + uint16_t *last_line; + int i; + + memmove(vga_memory, (uint16_t *)vga_memory + VGA_COLUMNS, + VGA_MEMORY_SIZE - (VGA_COLUMNS * 2)); + last_line = (uint16_t *)vga_memory + (VGA_COLUMNS * (VGA_LINES - 1)); + + for(i = 0; i < VGA_COLUMNS; i++) + last_line[i] = VGA_BLANK; +} + +void +vga_write_byte(uint8_t byte) +{ + if (byte == '\r') + return; + else if (byte == '\n') { + vga_cursor += VGA_COLUMNS - vga_get_cursor_column(); + + if (vga_cursor >= (VGA_LINES * VGA_COLUMNS)) { + vga_scroll_lines(); + vga_cursor -= VGA_COLUMNS; + } + + vga_set_cursor_position(vga_cursor); + } else if (byte == '\b') { + if (vga_cursor > 0) { + vga_cursor--; + ((uint16_t *)vga_memory)[vga_cursor] = VGA_BLANK; + vga_set_cursor_position(vga_cursor); + } + } else if (byte == '\t') { + int i; + + for(i = 0; i < VGA_TABULATION_SPACES; i++) + vga_write_byte(' '); + } else { + if ((vga_cursor + 1) >= VGA_COLUMNS * VGA_LINES) { + vga_scroll_lines(); + vga_cursor -= VGA_COLUMNS; + } + + ((uint16_t *)vga_memory)[vga_cursor] = ((VGA_FOREGROUND_COLOR << 8) + | byte); + vga_cursor++; + vga_set_cursor_position(vga_cursor); + } +} + +void console_write_byte(char c) __alias("vga_write_byte"); |