diff options
Diffstat (limited to 'arch/x86/machine/cga.c')
| -rw-r--r-- | arch/x86/machine/cga.c | 184 |
1 files changed, 184 insertions, 0 deletions
diff --git a/arch/x86/machine/cga.c b/arch/x86/machine/cga.c new file mode 100644 index 00000000..6e4ffc0d --- /dev/null +++ b/arch/x86/machine/cga.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 <kern/macros.h> +#include <kern/stdint.h> +#include <kern/string.h> +#include <machine/io.h> +#include <machine/pmap.h> +#include <machine/cga.h> + +/* + * Screen dimensions. + */ +#define CGA_COLUMNS 80 +#define CGA_LINES 25 + +/* + * Text mode mapped memory and size. + */ +#define CGA_MEMORY 0xb8000 +#define CGA_MEMORY_SIZE (CGA_COLUMNS * CGA_LINES * 2) + +/* + * I/O ports. + */ +#define CGA_MISC_OUTPUT_REGISTER_READ 0x3cc +#define CGA_MISC_OUTPUT_REGISTER_WRITE 0x3c2 +#define CGA_CRTC_ADDRESS_REGISTER 0x3d4 +#define CGA_CRTC_DATA_REGISTER 0x3d5 + +/* + * CRTC registers. + */ +#define CGA_CRTC_CURSOR_LOCATION_HIGH_REGISTER 0xe +#define CGA_CRTC_CURSOR_LOCATION_LOW_REGISTER 0xf + +/* + * Foreground screen color. + */ +#define CGA_FOREGROUND_COLOR 0x7 + +/* + * Blank space 16 bits word. + */ +#define CGA_BLANK ((CGA_FOREGROUND_COLOR << 8) | ' ') + +/* + * Number of spaces to display for a tabulation. + */ +#define CGA_TABULATION_SPACES 8 + +static uint8_t *cga_memory; +static uint16_t cga_cursor; + +static uint16_t +cga_get_cursor_position(void) +{ + uint16_t tmp; + + io_write_byte(CGA_CRTC_ADDRESS_REGISTER, + CGA_CRTC_CURSOR_LOCATION_HIGH_REGISTER); + tmp = io_read_byte(CGA_CRTC_DATA_REGISTER) << 8; + io_write_byte(CGA_CRTC_ADDRESS_REGISTER, + CGA_CRTC_CURSOR_LOCATION_LOW_REGISTER); + tmp |= io_read_byte(CGA_CRTC_DATA_REGISTER); + + return tmp; +} + +static void +cga_set_cursor_position(uint16_t position) +{ + io_write_byte(CGA_CRTC_ADDRESS_REGISTER, + CGA_CRTC_CURSOR_LOCATION_HIGH_REGISTER); + io_write_byte(CGA_CRTC_DATA_REGISTER, position >> 8); + io_write_byte(CGA_CRTC_ADDRESS_REGISTER, + CGA_CRTC_CURSOR_LOCATION_LOW_REGISTER); + io_write_byte(CGA_CRTC_DATA_REGISTER, position & 0xff); +} + +static uint8_t +cga_get_cursor_column(void) +{ + return cga_cursor % CGA_COLUMNS; +} + +void __init +cga_setup(void) +{ + uint8_t misc_output_register; + unsigned long va; + + va = pmap_bootalloc(1); + pmap_kenter(va, CGA_MEMORY); + cga_memory = (uint8_t *)va; + + /* + * Check if the Input/Output Address Select bit is set. + */ + misc_output_register = io_read_byte(CGA_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(CGA_MISC_OUTPUT_REGISTER_WRITE, misc_output_register); + } + + cga_cursor = cga_get_cursor_position(); +} + +static void +cga_scroll_lines(void) +{ + uint16_t *last_line; + int i; + + memmove(cga_memory, (uint16_t *)cga_memory + CGA_COLUMNS, + CGA_MEMORY_SIZE - (CGA_COLUMNS * 2)); + last_line = (uint16_t *)cga_memory + (CGA_COLUMNS * (CGA_LINES - 1)); + + for(i = 0; i < CGA_COLUMNS; i++) + last_line[i] = CGA_BLANK; +} + +void +cga_write_byte(uint8_t byte) +{ + if (byte == '\r') + return; + else if (byte == '\n') { + cga_cursor += CGA_COLUMNS - cga_get_cursor_column(); + + if (cga_cursor >= (CGA_LINES * CGA_COLUMNS)) { + cga_scroll_lines(); + cga_cursor -= CGA_COLUMNS; + } + + cga_set_cursor_position(cga_cursor); + } else if (byte == '\b') { + if (cga_cursor > 0) { + cga_cursor--; + ((uint16_t *)cga_memory)[cga_cursor] = CGA_BLANK; + cga_set_cursor_position(cga_cursor); + } + } else if (byte == '\t') { + int i; + + for(i = 0; i < CGA_TABULATION_SPACES; i++) + cga_write_byte(' '); + } else { + if ((cga_cursor + 1) >= CGA_COLUMNS * CGA_LINES) { + cga_scroll_lines(); + cga_cursor -= CGA_COLUMNS; + } + + ((uint16_t *)cga_memory)[cga_cursor] = ((CGA_FOREGROUND_COLOR << 8) + | byte); + cga_cursor++; + cga_set_cursor_position(cga_cursor); + } +} + +void console_write_byte(char c) __alias("cga_write_byte"); |