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
13 /****************************************************************
15 ****************************************************************/
17 // Call a function with a specified register state. Note that on
18 // return, the interrupt enable/disable flag may be altered.
20 call16(struct bregs *callregs)
28 "calll __call16_from32"
30 : "+a" (callregs), "+m" (*callregs)
32 : "ebx", "ecx", "edx", "esi", "edi", "cc", "memory");
36 call16big(struct bregs *callregs)
40 "calll __call16big_from32"
41 : "+a" (callregs), "+m" (*callregs)
43 : "ebx", "ecx", "edx", "esi", "edi", "cc", "memory");
47 __call16_int(struct bregs *callregs, u16 offset)
50 callregs->code.seg = GET_SEG(CS);
52 callregs->code.seg = SEG_BIOS;
53 callregs->code.offset = offset;
57 // Switch to the extra stack in ebda and call a function.
59 stack_hop(u32 eax, u32 edx, u32 ecx, void *func)
62 u16 ebda_seg = get_ebda_seg(), bkup_ss;
65 // Backup current %ss/%esp values.
68 // Copy ebda seg to %ds/%ss and set %esp
74 // Restore segments and stack
78 : "+a" (eax), "+d" (edx), "+c" (ecx), "=&r" (bkup_ss), "=&r" (bkup_esp)
79 : "i" (EBDA_OFFSET_TOP_STACK), "r" (ebda_seg), "m" (*(u8*)func)
84 // 16bit trampoline for enabling irqs from 32bit mode.
86 " .global trampoline_yield\n"
92 // Briefly permit irqs to occur.
106 extern void trampoline_yield();
109 br.code.seg = SEG_BIOS;
110 br.code.offset = (u32)&trampoline_yield;
115 /****************************************************************
117 ****************************************************************/
119 // Sum the bytes in the specified area.
121 checksum_far(u16 buf_seg, void *buf_far, u32 len)
123 SET_SEG(ES, buf_seg);
126 for (i=0; i<len; i++)
127 sum += GET_VAR(ES, ((u8*)buf_far)[i]);
132 checksum(void *buf, u32 len)
134 return checksum_far(GET_SEG(SS), buf, len);
138 strlen(const char *s)
140 if (__builtin_constant_p(s))
141 return __builtin_strlen(s);
148 // Compare two areas of memory.
150 memcmp(const void *s1, const void *s2, size_t n)
153 if (*(u8*)s1 != *(u8*)s2)
154 return *(u8*)s1 < *(u8*)s2 ? -1 : 1;
162 // Compare two strings.
164 strcmp(const char *s1, const char *s2)
168 return *s1 < *s2 ? -1 : 1;
177 memset_far(u16 d_seg, void *d_far, u8 c, size_t len)
181 "rep stosb %%es:(%%di)"
182 : "+c"(len), "+D"(d_far)
188 memset16_far(u16 d_seg, void *d_far, u16 c, size_t len)
193 "rep stosw %%es:(%%di)"
194 : "+c"(len), "+D"(d_far)
200 memset(void *s, int c, size_t n)
203 ((char *)s)[--n] = c;
208 memcpy_far(u16 d_seg, void *d_far, u16 s_seg, const void *s_far, size_t len)
215 "rep movsb (%%si),%%es:(%%di)\n"
217 : "=&r"(bkup_ds), "+c"(len), "+S"(s_far), "+D"(d_far)
224 memcpy(void *d1, const void *s1, size_t len)
226 #define memcpy __builtin_memcpy
229 SET_SEG(ES, GET_SEG(SS));
231 if (((u32)d1 | (u32)s1 | len) & 3) {
232 // non-aligned memcpy
234 "rep movsb (%%esi),%%es:(%%edi)"
235 : "+c"(len), "+S"(s1), "+D"(d)
239 // Common case - use 4-byte copy
242 "rep movsl (%%esi),%%es:(%%edi)"
243 : "+c"(len), "+S"(s1), "+D"(d)
249 memmove(void *d, const void *s, size_t len)
252 return memcpy(d, s, len);
257 *(char*)d = *(char*)s;
265 // Copy a string - truncating it if necessary.
267 strtcpy(char *dest, const char *src, size_t len)
270 while (len-- && *src != '\0')
277 /****************************************************************
279 ****************************************************************/
281 // Wait for 'usec' microseconds using (with irqs enabled) using int 1586.
286 memset(&br, 0, sizeof(br));
291 call16_int(0x15, &br);
294 // See if a keystroke is pending in the keyboard buffer.
296 check_for_keystroke()
299 memset(&br, 0, sizeof(br));
302 call16_int(0x16, &br);
303 return !(br.flags & F_ZF);
306 // Return a keystroke - waiting forever if necessary.
311 memset(&br, 0, sizeof(br));
313 call16_int(0x16, &br);
317 // Read a keystroke - waiting up to 'msec' milliseconds.
319 get_keystroke(int msec)
322 if (check_for_keystroke())
323 return get_raw_keystroke();