1 /* kernel.c - the C part of the kernel */ 2 /* Copyright (C) 1999 Free Software Foundation, Inc. 3 4 This program is free software; you can redistribute it and/or modify 5 it under the terms of the GNU General Public License as published by 6 the Free Software Foundation; either version 2 of the License, or 7 (at your option) any later version. 8 9 This program is distributed in the hope that it will be useful, 10 but WITHOUT ANY WARRANTY; without even the implied warranty of 11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 12 GNU General Public License for more details. 13 14 You should have received a copy of the GNU General Public License 15 along with this program; if not, write to the Free Software 16 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */ 17 18 #include <multiboot.h> 19 20 /* Macros. */ 21 22 /* Check if the bit BIT in FLAGS is set. */ 23 #define CHECK_FLAG(flags,bit) ((flags) & (1 << (bit))) 24 25 /* Some screen stuff. */ 26 /* The number of columns. */ 27 #define COLUMNS 80 28 /* The number of lines. */ 29 #define LINES 24 30 /* The attribute of an character. */ 31 #define ATTRIBUTE 7 32 /* The video memory address. */ 33 #define VIDEO 0xB8000 34 35 /* Variables. */ 36 /* Save the X position. */ 37 static int xpos; 38 /* Save the Y position. */ 39 static int ypos; 40 /* Point to the video memory. */ 41 static volatile unsigned char *video; 42 43 /* Forward declarations. */ 44 void cmain (unsigned long magic, unsigned long addr); 45 static void cls (void); 46 static void itoa (char *buf, int base, int d); 47 static void putchar (int c); 48 void printf (const char *format, ...); 49 50 /* Check if MAGIC is valid and print the Multiboot information structure 51 pointed by ADDR. */ 52 void 53 cmain (unsigned long magic, unsigned long addr) 54 { 55 multiboot_info_t *mbi; 56 57 /* Clear the screen. */ 58 cls (); 59 60 /* Am I booted by a Multiboot-compliant boot loader? */ 61 if (magic != MULTIBOOT_BOOTLOADER_MAGIC) 62 { 63 printf ("Invalid magic number: 0x%x\n", (unsigned) magic); 64 return; 65 } 66 67 /* Set MBI to the address of the Multiboot information structure. */ 68 mbi = (multiboot_info_t *) addr; 69 70 /* Print out the flags. */ 71 printf ("flags = 0x%x\n", (unsigned) mbi->flags); 72 73 /* Are mem_* valid? */ 74 if (CHECK_FLAG (mbi->flags, 0)) 75 printf ("mem_lower = %uKB, mem_upper = %uKB\n", 76 (unsigned) mbi->mem_lower, (unsigned) mbi->mem_upper); 77 78 /* Is boot_device valid? */ 79 if (CHECK_FLAG (mbi->flags, 1)) 80 printf ("boot_device = 0x%x\n", (unsigned) mbi->boot_device); 81 82 /* Is the command line passed? */ 83 if (CHECK_FLAG (mbi->flags, 2)) 84 printf ("cmdline = %s\n", (char *) mbi->cmdline); 85 86 /* Are mods_* valid? */ 87 if (CHECK_FLAG (mbi->flags, 3)) 88 { 89 module_t *mod; 90 int i; 91 92 printf ("mods_count = %d, mods_addr = 0x%x\n", 93 (int) mbi->mods_count, (int) mbi->mods_addr); 94 for (i = 0, mod = (module_t *) mbi->mods_addr; 95 i < mbi->mods_count; 96 i++, mod++) 97 printf (" mod_start = 0x%x, mod_end = 0x%x, string = %s\n", 98 (unsigned) mod->mod_start, 99 (unsigned) mod->mod_end, 100 (char *) mod->string); 101 } 102 103 /* Bits 4 and 5 are mutually exclusive! */ 104 if (CHECK_FLAG (mbi->flags, 4) && CHECK_FLAG (mbi->flags, 5)) 105 { 106 printf ("Both bits 4 and 5 are set.\n"); 107 return; 108 } 109 110 /* Is the symbol table of a.out valid? */ 111 if (CHECK_FLAG (mbi->flags, 4)) 112 { 113 aout_symbol_table_t *aout_sym = &(mbi->u.aout_sym); 114 115 printf ("aout_symbol_table: tabsize = 0x%0x, " 116 "strsize = 0x%x, addr = 0x%x\n", 117 (unsigned) aout_sym->tabsize, 118 (unsigned) aout_sym->strsize, 119 (unsigned) aout_sym->addr); 120 } 121 122 /* Is the section header table of ELF valid? */ 123 if (CHECK_FLAG (mbi->flags, 5)) 124 { 125 elf_section_header_table_t *elf_sec = &(mbi->u.elf_sec); 126 127 printf ("elf_sec: num = %u, size = 0x%x," 128 " addr = 0x%x, shndx = 0x%x\n", 129 (unsigned) elf_sec->num, (unsigned) elf_sec->size, 130 (unsigned) elf_sec->addr, (unsigned) elf_sec->shndx); 131 } 132 133 /* Are mmap_* valid? */ 134 if (CHECK_FLAG (mbi->flags, 6)) 135 { 136 memory_map_t *mmap; 137 138 printf ("mmap_addr = 0x%x, mmap_length = 0x%x\n", 139 (unsigned) mbi->mmap_addr, (unsigned) mbi->mmap_length); 140 for (mmap = (memory_map_t *) mbi->mmap_addr; 141 (unsigned long) mmap < mbi->mmap_addr + mbi->mmap_length; 142 mmap = (memory_map_t *) ((unsigned long) mmap 143 + mmap->size + sizeof (mmap->size))) 144 printf (" size = 0x%x, base_addr = 0x%x%x," 145 " length = 0x%x%x, type = 0x%x\n", 146 (unsigned) mmap->size, 147 (unsigned) mmap->base_addr_high, 148 (unsigned) mmap->base_addr_low, 149 (unsigned) mmap->length_high, 150 (unsigned) mmap->length_low, 151 (unsigned) mmap->type); 152 } 153 } 154 155 /* Clear the screen and initialize VIDEO, XPOS and YPOS. */ 156 static void 157 cls (void) 158 { 159 int i; 160 161 video = (unsigned char *) VIDEO; 162 163 for (i = 0; i < COLUMNS * LINES * 2; i++) 164 *(video + i) = 0; 165 166 xpos = 0; 167 ypos = 0; 168 } 169 170 /* Convert the integer D to a string and save the string in BUF. If 171 BASE is equal to 'd', interpret that D is decimal, and if BASE is 172 equal to 'x', interpret that D is hexadecimal. */ 173 static void 174 itoa (char *buf, int base, int d) 175 { 176 char *p = buf; 177 char *p1, *p2; 178 unsigned long ud = d; 179 int divisor = 10; 180 181 /* If %d is specified and D is minus, put `-' in the head. */ 182 if (base == 'd' && d < 0) 183 { 184 *p++ = '-'; 185 buf++; 186 ud = -d; 187 } 188 else if (base == 'x') 189 divisor = 16; 190 191 /* Divide UD by DIVISOR until UD == 0. */ 192 do 193 { 194 int remainder = ud % divisor; 195 196 *p++ = (remainder < 10) ? remainder + '0' : remainder + 'a' - 10; 197 } 198 while (ud /= divisor); 199 200 /* Terminate BUF. */ 201 *p = 0; 202 203 /* Reverse BUF. */ 204 p1 = buf; 205 p2 = p - 1; 206 while (p1 < p2) 207 { 208 char tmp = *p1; 209 *p1 = *p2; 210 *p2 = tmp; 211 p1++; 212 p2--; 213 } 214 } 215 216 /* Put the character C on the screen. */ 217 static void 218 putchar (int c) 219 { 220 if (c == '\n' || c == '\r') 221 { 222 newline: 223 xpos = 0; 224 ypos++; 225 if (ypos >= LINES) 226 ypos = 0; 227 return; 228 } 229 230 *(video + (xpos + ypos * COLUMNS) * 2) = c & 0xFF; 231 *(video + (xpos + ypos * COLUMNS) * 2 + 1) = ATTRIBUTE; 232 233 xpos++; 234 if (xpos >= COLUMNS) 235 goto newline; 236 } 237 238 /* Format a string and print it on the screen, just like the libc 239 function printf. */ 240 void 241 printf (const char *format, ...) 242 { 243 char **arg = (char **) &format; 244 int c; 245 char buf[20]; 246 247 arg++; 248 249 while ((c = *format++) != 0) 250 { 251 if (c != '%') 252 putchar (c); 253 else 254 { 255 char *p; 256 257 c = *format++; 258 switch (c) 259 { 260 case 'd': 261 case 'u': 262 case 'x': 263 itoa (buf, c, *((int *) arg++)); 264 p = buf; 265 goto string; 266 break; 267 268 case 's': 269 p = *arg++; 270 if (! p) 271 p = "(null)"; 272 273 string: 274 while (*p) 275 putchar (*p++); 276 break; 277 278 default: 279 putchar (*((int *) arg++)); 280 break; 281 } 282 } 283 } 284 } 285