153 lines
4.5 KiB
C
153 lines
4.5 KiB
C
/* Copyright (C) 2004 The SOS Team
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Copyright (C) 1999 Free Software Foundation, Inc.
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This program is free software; you can redistribute it and/or
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modify it under the terms of the GNU General Public License
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as published by the Free Software Foundation; either version 2
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of the License, or (at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
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USA.
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*/
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/* Include definitions of the multiboot standard */
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#include <bootstrap/multiboot.h>
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#include <hwcore/idt.h>
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#include <hwcore/gdt.h>
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#include <hwcore/irq.h>
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#include <hwcore/exception.h>
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#include <hwcore/i8254.h>
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#include <sos/klibc.h>
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#include <sos/assert.h>
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#include <drivers/x86_videomem.h>
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#include <drivers/bochs.h>
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/* Helper function to display each bits of a 32bits integer on the
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screen as dark or light carrets */
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static void display_bits(unsigned char row, unsigned char col,
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unsigned char attribute,
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sos_ui32_t integer)
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{
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int i;
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/* Scan each bit of the integer, MSb first */
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for (i = 31 ; i >= 0 ; i--)
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{
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/* Test if bit i of 'integer' is set */
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int bit_i = (integer & (1 << i));
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/* Ascii 219 => dark carret, Ascii 177 => light carret */
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unsigned char ascii_code = bit_i?219:177;
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sos_x86_videomem_putchar(row, col++,
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attribute,
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ascii_code);
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}
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}
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/* Clock IRQ handler */
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static void clk_it(int intid)
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{
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static sos_ui32_t clock_count = 0;
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display_bits(0, 48,
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SOS_X86_VIDEO_FG_LTGREEN | SOS_X86_VIDEO_BG_BLUE,
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clock_count);
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clock_count++;
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}
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/* Division by zero exception handler */
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static void divide_ex(int exid)
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{
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static sos_ui32_t div_count = 0;
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display_bits(0, 0,
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SOS_X86_VIDEO_FG_LTRED | SOS_X86_VIDEO_BG_BLUE,
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div_count);
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div_count++;
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}
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/* The C entry point of our operating system */
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void sos_main(unsigned long magic, unsigned long addr)
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{
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unsigned i;
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/* Grub sends us a structure, called multiboot_info_t with a lot of
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precious informations about the system, see the multiboot
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documentation for more information. */
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multiboot_info_t *mbi;
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mbi = (multiboot_info_t *) addr;
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/* Setup bochs and console, and clear the console */
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sos_bochs_setup();
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sos_x86_videomem_setup();
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sos_x86_videomem_cls(SOS_X86_VIDEO_BG_BLUE);
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/* Greetings from SOS */
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if (magic == MULTIBOOT_BOOTLOADER_MAGIC)
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/* Loaded with Grub */
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sos_x86_videomem_printf(1, 0,
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SOS_X86_VIDEO_FG_YELLOW | SOS_X86_VIDEO_BG_BLUE,
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"Welcome From GRUB to %s%c RAM is %dMB (upper mem = 0x%x kB)",
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"SOS", ',',
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(unsigned)(mbi->mem_upper >> 10) + 1,
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(unsigned)mbi->mem_upper);
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else
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/* Not loaded with grub */
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sos_x86_videomem_printf(1, 0,
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SOS_X86_VIDEO_FG_YELLOW | SOS_X86_VIDEO_BG_BLUE,
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"Welcome to SOS");
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sos_bochs_putstring("Message in a bochs\n");
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/* Setup CPU segmentation and IRQ subsystem */
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sos_gdt_setup();
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sos_idt_setup();
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/* Setup SOS IRQs and exceptions subsystem */
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sos_exceptions_setup();
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sos_irq_setup();
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/* Configure the timer so as to raise the IRQ0 at a 100Hz rate */
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sos_i8254_set_frequency(100);
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/* Binding some HW interrupts and exceptions to software routines */
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sos_irq_set_routine(SOS_IRQ_TIMER,
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clk_it);
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sos_exception_set_routine(SOS_EXCEPT_DIVIDE_ERROR,
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divide_ex);
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/* Enabling the HW interrupts here, this will make the timer HW
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interrupt call our clk_it handler */
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asm volatile ("sti\n");
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/* Raise a rafale of 'division by 0' exceptions. All this code is
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not really needed (equivalent to a bare "i=1/0;"), except when
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compiling with -O3: "i=1/0;" is considered dead code with gcc
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-O3. */
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i = 10;
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while (1)
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{
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/* Stupid function call to fool gcc optimizations */
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sos_bochs_printf("i = 1 / %d...\n", i);
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i = 1 / i;
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}
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/* Will never print this since the "divide by zero" exception always
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returns to the faulting instruction (see Intel x86 doc vol 3,
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section 5.12), thus re-evaluating the "divide-by-zero" exprssion
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and raising the "divide by zero" exception again and again... */
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sos_x86_videomem_putstring(2, 0,
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SOS_X86_VIDEO_FG_LTRED | SOS_X86_VIDEO_BG_BLUE,
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"Invisible");
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return;
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}
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