From bb55beef914e7488350ad1d0419d4bc60ad63c99 Mon Sep 17 00:00:00 2001 From: Alex AUVOLAT Date: Fri, 28 Mar 2014 09:10:23 +0100 Subject: Import code for article1, 2, 3, 4 --- sos-code-article2/sos/main.c | 152 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 152 insertions(+) create mode 100644 sos-code-article2/sos/main.c (limited to 'sos-code-article2/sos/main.c') diff --git a/sos-code-article2/sos/main.c b/sos-code-article2/sos/main.c new file mode 100644 index 0000000..9d897b0 --- /dev/null +++ b/sos-code-article2/sos/main.c @@ -0,0 +1,152 @@ +/* Copyright (C) 2004 The SOS Team + Copyright (C) 1999 Free Software Foundation, Inc. + + 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 2 + 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, write to the Free Software + Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, + USA. +*/ + +/* Include definitions of the multiboot standard */ +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + + +/* Helper function to display each bits of a 32bits integer on the + screen as dark or light carrets */ +static void display_bits(unsigned char row, unsigned char col, + unsigned char attribute, + sos_ui32_t integer) +{ + int i; + /* Scan each bit of the integer, MSb first */ + for (i = 31 ; i >= 0 ; i--) + { + /* Test if bit i of 'integer' is set */ + int bit_i = (integer & (1 << i)); + /* Ascii 219 => dark carret, Ascii 177 => light carret */ + unsigned char ascii_code = bit_i?219:177; + sos_x86_videomem_putchar(row, col++, + attribute, + ascii_code); + } +} + + +/* Clock IRQ handler */ +static void clk_it(int intid) +{ + static sos_ui32_t clock_count = 0; + + display_bits(0, 48, + SOS_X86_VIDEO_FG_LTGREEN | SOS_X86_VIDEO_BG_BLUE, + clock_count); + clock_count++; + +} + +/* Division by zero exception handler */ +static void divide_ex(int exid) +{ + static sos_ui32_t div_count = 0; + display_bits(0, 0, + SOS_X86_VIDEO_FG_LTRED | SOS_X86_VIDEO_BG_BLUE, + div_count); + div_count++; +} + +/* The C entry point of our operating system */ +void sos_main(unsigned long magic, unsigned long addr) +{ + unsigned i; + + /* Grub sends us a structure, called multiboot_info_t with a lot of + precious informations about the system, see the multiboot + documentation for more information. */ + multiboot_info_t *mbi; + mbi = (multiboot_info_t *) addr; + + /* Setup bochs and console, and clear the console */ + sos_bochs_setup(); + + sos_x86_videomem_setup(); + sos_x86_videomem_cls(SOS_X86_VIDEO_BG_BLUE); + + /* Greetings from SOS */ + if (magic == MULTIBOOT_BOOTLOADER_MAGIC) + /* Loaded with Grub */ + sos_x86_videomem_printf(1, 0, + SOS_X86_VIDEO_FG_YELLOW | SOS_X86_VIDEO_BG_BLUE, + "Welcome From GRUB to %s%c RAM is %dMB (upper mem = 0x%x kB)", + "SOS", ',', + (unsigned)(mbi->mem_upper >> 10) + 1, + (unsigned)mbi->mem_upper); + else + /* Not loaded with grub */ + sos_x86_videomem_printf(1, 0, + SOS_X86_VIDEO_FG_YELLOW | SOS_X86_VIDEO_BG_BLUE, + "Welcome to SOS"); + + sos_bochs_putstring("Message in a bochs\n"); + + /* Setup CPU segmentation and IRQ subsystem */ + sos_gdt_setup(); + sos_idt_setup(); + + /* Setup SOS IRQs and exceptions subsystem */ + sos_exceptions_setup(); + sos_irq_setup(); + + /* Configure the timer so as to raise the IRQ0 at a 100Hz rate */ + sos_i8254_set_frequency(100); + + + /* Binding some HW interrupts and exceptions to software routines */ + sos_irq_set_routine(SOS_IRQ_TIMER, + clk_it); + sos_exception_set_routine(SOS_EXCEPT_DIVIDE_ERROR, + divide_ex); + /* Enabling the HW interrupts here, this will make the timer HW + interrupt call our clk_it handler */ + asm volatile ("sti\n"); + + /* Raise a rafale of 'division by 0' exceptions. All this code is + not really needed (equivalent to a bare "i=1/0;"), except when + compiling with -O3: "i=1/0;" is considered dead code with gcc + -O3. */ + i = 10; + while (1) + { + /* Stupid function call to fool gcc optimizations */ + sos_bochs_printf("i = 1 / %d...\n", i); + i = 1 / i; + } + + /* Will never print this since the "divide by zero" exception always + returns to the faulting instruction (see Intel x86 doc vol 3, + section 5.12), thus re-evaluating the "divide-by-zero" exprssion + and raising the "divide by zero" exception again and again... */ + sos_x86_videomem_putstring(2, 0, + SOS_X86_VIDEO_FG_LTRED | SOS_X86_VIDEO_BG_BLUE, + "Invisible"); + + return; +} -- cgit v1.2.3