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;
142 MainThread.next = &MainThread;
143 MainThread.stackpos = NULL;
150 if (esp <= BUILD_STACK_ADDR)
152 return (void*)ALIGN_DOWN(esp, THREADSTACKSIZE);
155 // Briefly permit irqs to occur.
160 // In 16bit mode, just directly check irqs.
164 if (! CONFIG_THREADS) {
168 struct thread_info *cur = getCurThread();
169 if (cur == &MainThread)
170 // Permit irqs to fire
173 // Switch to the next thread
174 struct thread_info *next = cur->next;
176 " pushl $1f\n" // store return pc
177 " pushl %%ebp\n" // backup %ebp
178 " movl %%esp, 4(%%eax)\n" // cur->stackpos = %esp
179 " movl 4(%%ecx), %%esp\n" // %esp = next->stackpos
180 " popl %%ebp\n" // restore %ebp
181 " retl\n" // restore pc
183 : "+a"(cur), "+c"(next)
185 : "ebx", "edx", "esi", "edi", "cc", "memory");
188 // Last thing called from a thread (called on "next" stack).
190 __end_thread(struct thread_info *old)
192 struct thread_info *pos = &MainThread;
193 while (pos->next != old)
195 pos->next = old->next;
197 dprintf(DEBUG_thread, "\\%08x/ End thread\n", (u32)old);
201 run_thread(void (*func)(void*), void *data)
204 if (! CONFIG_THREADS)
206 struct thread_info *thread;
207 thread = memalign_tmphigh(THREADSTACKSIZE, THREADSTACKSIZE);
211 thread->stackpos = (void*)thread + THREADSTACKSIZE;
212 struct thread_info *cur = getCurThread();
213 thread->next = cur->next;
216 dprintf(DEBUG_thread, "/%08x\\ Start thread\n", (u32)thread);
219 " pushl $1f\n" // store return pc
220 " pushl %%ebp\n" // backup %ebp
221 " movl %%esp, 4(%%edx)\n" // cur->stackpos = %esp
222 " movl 4(%%ebx), %%esp\n" // %esp = thread->stackpos
223 " calll *%%ecx\n" // Call func
226 " movl (%%ebx), %%ecx\n" // %ecx = thread->next
227 " movl 4(%%ecx), %%esp\n" // %esp = next->stackpos
228 " movl %%ebx, %%eax\n"
229 " calll %4\n" // call __end_thread(thread)
230 " popl %%ebp\n" // restore %ebp
231 " retl\n" // restore pc
233 : "+a"(data), "+c"(func), "+b"(thread), "+d"(cur)
234 : "m"(*(u8*)__end_thread)
235 : "esi", "edi", "cc", "memory");
246 if (! CONFIG_THREADS)
248 while (MainThread.next != &MainThread)
253 /****************************************************************
255 ****************************************************************/
257 // Sum the bytes in the specified area.
259 checksum_far(u16 buf_seg, void *buf_far, u32 len)
261 SET_SEG(ES, buf_seg);
264 for (i=0; i<len; i++)
265 sum += GET_VAR(ES, ((u8*)buf_far)[i]);
270 checksum(void *buf, u32 len)
272 return checksum_far(GET_SEG(SS), buf, len);
276 strlen(const char *s)
278 if (__builtin_constant_p(s))
279 return __builtin_strlen(s);
286 // Compare two areas of memory.
288 memcmp(const void *s1, const void *s2, size_t n)
291 if (*(u8*)s1 != *(u8*)s2)
292 return *(u8*)s1 < *(u8*)s2 ? -1 : 1;
300 // Compare two strings.
302 strcmp(const char *s1, const char *s2)
306 return *s1 < *s2 ? -1 : 1;
315 memset_far(u16 d_seg, void *d_far, u8 c, size_t len)
319 "rep stosb %%es:(%%di)"
320 : "+c"(len), "+D"(d_far)
326 memset16_far(u16 d_seg, void *d_far, u16 c, size_t len)
331 "rep stosw %%es:(%%di)"
332 : "+c"(len), "+D"(d_far)
338 memset(void *s, int c, size_t n)
341 ((char *)s)[--n] = c;
346 memcpy_far(u16 d_seg, void *d_far, u16 s_seg, const void *s_far, size_t len)
353 "rep movsb (%%si),%%es:(%%di)\n"
355 : "=&r"(bkup_ds), "+c"(len), "+S"(s_far), "+D"(d_far)
362 memcpy(void *d1, const void *s1, size_t len)
364 #define memcpy __builtin_memcpy
367 SET_SEG(ES, GET_SEG(SS));
369 if (((u32)d1 | (u32)s1 | len) & 3) {
370 // non-aligned memcpy
372 "rep movsb (%%esi),%%es:(%%edi)"
373 : "+c"(len), "+S"(s1), "+D"(d)
377 // Common case - use 4-byte copy
380 "rep movsl (%%esi),%%es:(%%edi)"
381 : "+c"(len), "+S"(s1), "+D"(d)
386 // Copy from memory mapped IO. IO mem is very slow, so yield
387 // periodically. 'len' must be 4 byte aligned.
389 iomemcpy(void *d, const void *s, u32 len)
399 "rep movsl (%%esi),%%es:(%%edi)"
400 : "+c"(copylen), "+S"(s), "+D"(d)
407 memmove(void *d, const void *s, size_t len)
410 return memcpy(d, s, len);
415 *(char*)d = *(char*)s;
423 // Copy a string - truncating it if necessary.
425 strtcpy(char *dest, const char *src, size_t len)
428 while (len-- && *src != '\0')
435 /****************************************************************
437 ****************************************************************/
439 // Wait for 'usec' microseconds using (with irqs enabled) using int 1586.
444 memset(&br, 0, sizeof(br));
449 call16_int(0x15, &br);
452 // See if a keystroke is pending in the keyboard buffer.
454 check_for_keystroke()
457 memset(&br, 0, sizeof(br));
460 call16_int(0x16, &br);
461 return !(br.flags & F_ZF);
464 // Return a keystroke - waiting forever if necessary.
469 memset(&br, 0, sizeof(br));
471 call16_int(0x16, &br);
475 // Read a keystroke - waiting up to 'msec' milliseconds.
477 get_keystroke(int msec)
480 if (check_for_keystroke())
481 return get_raw_keystroke();