1 // Misc utility functions.
3 // Copyright (C) 2008,2009 Kevin O'Connor <kevin@koconnor.net>
5 // This file may be distributed under the terms of the GNU LGPLv3 license.
7 #include "util.h" // call16
8 #include "bregs.h" // struct bregs
9 #include "farptr.h" // GET_FLATPTR
10 #include "biosvar.h" // get_ebda_seg
12 static inline u32 getesp() {
14 asm("movl %%esp, %0" : "=rm"(esp));
19 /****************************************************************
21 ****************************************************************/
23 // Call a function with a specified register state. Note that on
24 // return, the interrupt enable/disable flag may be altered.
26 call16(struct bregs *callregs)
28 if (!MODE16 && getesp() > BUILD_STACK_ADDR)
29 panic("call16 with invalid stack\n");
36 "calll __call16_from32"
38 : "+a" (callregs), "+m" (*callregs)
40 : "ebx", "ecx", "edx", "esi", "edi", "cc", "memory");
44 call16big(struct bregs *callregs)
47 if (getesp() > BUILD_STACK_ADDR)
48 panic("call16 with invalid stack\n");
50 "calll __call16big_from32"
51 : "+a" (callregs), "+m" (*callregs)
53 : "ebx", "ecx", "edx", "esi", "edi", "cc", "memory");
57 __call16_int(struct bregs *callregs, u16 offset)
60 callregs->code.seg = GET_SEG(CS);
62 callregs->code.seg = SEG_BIOS;
63 callregs->code.offset = offset;
67 // Switch to the extra stack in ebda and call a function.
69 stack_hop(u32 eax, u32 edx, u32 ecx, void *func)
72 u16 ebda_seg = get_ebda_seg(), bkup_ss;
75 // Backup current %ss/%esp values.
78 // Copy ebda seg to %ds/%ss and set %esp
84 // Restore segments and stack
88 : "+a" (eax), "+d" (edx), "+c" (ecx), "=&r" (bkup_ss), "=&r" (bkup_esp)
89 : "i" (EBDA_OFFSET_TOP_STACK), "r" (ebda_seg), "m" (*(u8*)func)
94 // 16bit trampoline for enabling irqs from 32bit mode.
96 " .global trampoline_checkirqs\n"
97 "trampoline_checkirqs:\n"
105 extern void trampoline_checkirqs();
108 br.code.seg = SEG_BIOS;
109 br.code.offset = (u32)&trampoline_checkirqs;
126 /****************************************************************
128 ****************************************************************/
130 #define THREADSTACKSIZE 4096
133 struct thread_info *next;
137 struct thread_info MainThread = {&MainThread, NULL};
143 if (esp <= BUILD_STACK_ADDR)
145 return (void*)ALIGN_DOWN(esp, THREADSTACKSIZE);
148 // Briefly permit irqs to occur.
153 // In 16bit mode, just directly check irqs.
157 if (! CONFIG_THREADS) {
161 struct thread_info *cur = getCurThread();
162 if (cur == &MainThread)
163 // Permit irqs to fire
166 // Switch to the next thread
167 struct thread_info *next = cur->next;
169 " pushl $1f\n" // store return pc
170 " pushl %%ebp\n" // backup %ebp
171 " movl %%esp, 4(%%eax)\n" // cur->stackpos = %esp
172 " movl 4(%%ecx), %%esp\n" // %esp = next->stackpos
173 " popl %%ebp\n" // restore %ebp
174 " retl\n" // restore pc
176 : "+a"(cur), "+c"(next)
178 : "ebx", "edx", "esi", "edi", "cc", "memory");
181 // Last thing called from a thread (called on "next" stack).
183 __end_thread(struct thread_info *old)
185 struct thread_info *pos = &MainThread;
186 while (pos->next != old)
188 pos->next = old->next;
190 dprintf(DEBUG_thread, "\\%08x/ End thread\n", (u32)old);
194 run_thread(void (*func)(void*), void *data)
197 if (! CONFIG_THREADS)
199 struct thread_info *thread;
200 thread = memalign_tmphigh(THREADSTACKSIZE, THREADSTACKSIZE);
204 thread->stackpos = (void*)thread + THREADSTACKSIZE;
205 struct thread_info *cur = getCurThread();
206 thread->next = cur->next;
209 dprintf(DEBUG_thread, "/%08x\\ Start thread\n", (u32)thread);
212 " pushl $1f\n" // store return pc
213 " pushl %%ebp\n" // backup %ebp
214 " movl %%esp, 4(%%edx)\n" // cur->stackpos = %esp
215 " movl 4(%%ebx), %%esp\n" // %esp = thread->stackpos
216 " calll *%%ecx\n" // Call func
219 " movl (%%ebx), %%ecx\n" // %ecx = thread->next
220 " movl 4(%%ecx), %%esp\n" // %esp = next->stackpos
221 " movl %%ebx, %%eax\n"
222 " calll %4\n" // call __end_thread(thread)
223 " popl %%ebp\n" // restore %ebp
224 " retl\n" // restore pc
226 : "+a"(data), "+c"(func), "+b"(thread), "+d"(cur)
227 : "m"(*(u8*)__end_thread)
228 : "esi", "edi", "cc", "memory");
239 if (! CONFIG_THREADS)
241 while (MainThread.next != &MainThread)
246 /****************************************************************
248 ****************************************************************/
250 // Sum the bytes in the specified area.
252 checksum_far(u16 buf_seg, void *buf_far, u32 len)
254 SET_SEG(ES, buf_seg);
257 for (i=0; i<len; i++)
258 sum += GET_VAR(ES, ((u8*)buf_far)[i]);
263 checksum(void *buf, u32 len)
265 return checksum_far(GET_SEG(SS), buf, len);
269 strlen(const char *s)
271 if (__builtin_constant_p(s))
272 return __builtin_strlen(s);
279 // Compare two areas of memory.
281 memcmp(const void *s1, const void *s2, size_t n)
284 if (*(u8*)s1 != *(u8*)s2)
285 return *(u8*)s1 < *(u8*)s2 ? -1 : 1;
293 // Compare two strings.
295 strcmp(const char *s1, const char *s2)
299 return *s1 < *s2 ? -1 : 1;
308 memset_far(u16 d_seg, void *d_far, u8 c, size_t len)
312 "rep stosb %%es:(%%di)"
313 : "+c"(len), "+D"(d_far)
319 memset16_far(u16 d_seg, void *d_far, u16 c, size_t len)
324 "rep stosw %%es:(%%di)"
325 : "+c"(len), "+D"(d_far)
331 memset(void *s, int c, size_t n)
334 ((char *)s)[--n] = c;
339 memcpy_far(u16 d_seg, void *d_far, u16 s_seg, const void *s_far, size_t len)
346 "rep movsb (%%si),%%es:(%%di)\n"
348 : "=&r"(bkup_ds), "+c"(len), "+S"(s_far), "+D"(d_far)
355 memcpy(void *d1, const void *s1, size_t len)
357 #define memcpy __builtin_memcpy
360 SET_SEG(ES, GET_SEG(SS));
362 if (((u32)d1 | (u32)s1 | len) & 3) {
363 // non-aligned memcpy
365 "rep movsb (%%esi),%%es:(%%edi)"
366 : "+c"(len), "+S"(s1), "+D"(d)
370 // Common case - use 4-byte copy
373 "rep movsl (%%esi),%%es:(%%edi)"
374 : "+c"(len), "+S"(s1), "+D"(d)
380 memmove(void *d, const void *s, size_t len)
383 return memcpy(d, s, len);
388 *(char*)d = *(char*)s;
396 // Copy a string - truncating it if necessary.
398 strtcpy(char *dest, const char *src, size_t len)
401 while (len-- && *src != '\0')
408 /****************************************************************
410 ****************************************************************/
412 // Wait for 'usec' microseconds using (with irqs enabled) using int 1586.
417 memset(&br, 0, sizeof(br));
422 call16_int(0x15, &br);
425 // See if a keystroke is pending in the keyboard buffer.
427 check_for_keystroke()
430 memset(&br, 0, sizeof(br));
433 call16_int(0x16, &br);
434 return !(br.flags & F_ZF);
437 // Return a keystroke - waiting forever if necessary.
442 memset(&br, 0, sizeof(br));
444 call16_int(0x16, &br);
448 // Read a keystroke - waiting up to 'msec' milliseconds.
450 get_keystroke(int msec)
453 if (check_for_keystroke())
454 return get_raw_keystroke();