| // Misc utility functions. |
| // |
| // Copyright (C) 2008,2009 Kevin O'Connor <kevin@koconnor.net> |
| // |
| // This file may be distributed under the terms of the GNU LGPLv3 license. |
| |
| #include "util.h" // call16 |
| #include "bregs.h" // struct bregs |
| #include "farptr.h" // GET_FLATPTR |
| #include "biosvar.h" // get_ebda_seg |
| |
| // Call a function with a specified register state. Note that on |
| // return, the interrupt enable/disable flag may be altered. |
| inline void |
| call16(struct bregs *callregs) |
| { |
| asm volatile( |
| #if MODE16 == 1 |
| "calll __call16\n" |
| "cli\n" |
| "cld" |
| #else |
| "calll __call16_from32" |
| #endif |
| : "+a" (callregs), "+m" (*callregs) |
| : |
| : "ebx", "ecx", "edx", "esi", "edi", "cc", "memory"); |
| } |
| |
| inline void |
| call16big(struct bregs *callregs) |
| { |
| extern void __force_link_error__call16big_only_in_32bit_mode(); |
| if (MODE16) |
| __force_link_error__call16big_only_in_32bit_mode(); |
| |
| asm volatile( |
| "calll __call16big_from32" |
| : "+a" (callregs), "+m" (*callregs) |
| : |
| : "ebx", "ecx", "edx", "esi", "edi", "cc", "memory"); |
| } |
| |
| inline void |
| __call16_int(struct bregs *callregs, u16 offset) |
| { |
| if (MODE16) |
| callregs->cs = GET_SEG(CS); |
| else |
| callregs->cs = SEG_BIOS; |
| callregs->ip = offset; |
| call16(callregs); |
| } |
| |
| inline void |
| call16_simpint(int nr, u32 *eax, u32 *flags) |
| { |
| extern void __force_link_error__call16_simpint_only_in_16bit_mode(); |
| if (!MODE16) |
| __force_link_error__call16_simpint_only_in_16bit_mode(); |
| |
| asm volatile( |
| "stc\n" |
| "int %2\n" |
| "pushfl\n" |
| "popl %1\n" |
| "cli\n" |
| "cld" |
| : "+a"(*eax), "=r"(*flags) |
| : "i"(nr) |
| : "cc", "memory"); |
| } |
| |
| // Switch to the extra stack in ebda and call a function. |
| inline u32 |
| stack_hop(u32 eax, u32 edx, u32 ecx, void *func) |
| { |
| extern void __force_link_error__stack_hop_only_in_16bit_mode(); |
| if (!MODE16) |
| __force_link_error__stack_hop_only_in_16bit_mode(); |
| |
| u16 ebda_seg = get_ebda_seg(), bkup_ss; |
| u32 bkup_esp; |
| asm volatile( |
| // Backup current %ss/%esp values. |
| "movw %%ss, %w3\n" |
| "movl %%esp, %4\n" |
| // Copy ebda seg to %ds/%ss and set %esp |
| "movw %w6, %%ds\n" |
| "movw %w6, %%ss\n" |
| "movl %5, %%esp\n" |
| // Call func |
| "calll %7\n" |
| // Restore segments and stack |
| "movw %w3, %%ds\n" |
| "movw %w3, %%ss\n" |
| "movl %4, %%esp" |
| : "+a" (eax), "+d" (edx), "+c" (ecx), "=&r" (bkup_ss), "=&r" (bkup_esp) |
| : "i" (EBDA_OFFSET_TOP_STACK), "r" (ebda_seg), "m" (*(u8*)func) |
| : "cc", "memory"); |
| return eax; |
| } |
| |
| // Sum the bytes in the specified area. |
| u8 |
| checksum_far(u16 buf_seg, void *buf_far, u32 len) |
| { |
| SET_SEG(ES, buf_seg); |
| u32 i; |
| u8 sum = 0; |
| for (i=0; i<len; i++) |
| sum += GET_VAR(ES, ((u8*)buf_far)[i]); |
| return sum; |
| } |
| |
| u8 |
| checksum(void *buf, u32 len) |
| { |
| return checksum_far(GET_SEG(SS), buf, len); |
| } |
| |
| size_t |
| strlen(const char *s) |
| { |
| if (__builtin_constant_p(s)) |
| return __builtin_strlen(s); |
| const char *p = s; |
| while (*p) |
| p++; |
| return p-s; |
| } |
| |
| // Compare two areas of memory. |
| int |
| memcmp(const void *s1, const void *s2, size_t n) |
| { |
| while (n) { |
| if (*(u8*)s1 != *(u8*)s2) |
| return *(u8*)s1 < *(u8*)s2 ? -1 : 1; |
| s1++; |
| s2++; |
| n--; |
| } |
| return 0; |
| } |
| |
| // Compare two strings. |
| int |
| strcmp(const char *s1, const char *s2) |
| { |
| for (;;) { |
| if (*s1 != *s2) |
| return *s1 < *s2 ? -1 : 1; |
| if (! *s1) |
| return 0; |
| s1++; |
| s2++; |
| } |
| } |
| |
| inline void |
| memset_far(u16 d_seg, void *d_far, u8 c, size_t len) |
| { |
| SET_SEG(ES, d_seg); |
| asm volatile( |
| "rep stosb %%es:(%%di)" |
| : "+c"(len), "+D"(d_far) |
| : "a"(c) |
| : "cc", "memory"); |
| } |
| |
| inline void |
| memset16_far(u16 d_seg, void *d_far, u16 c, size_t len) |
| { |
| len /= 2; |
| SET_SEG(ES, d_seg); |
| asm volatile( |
| "rep stosw %%es:(%%di)" |
| : "+c"(len), "+D"(d_far) |
| : "a"(c) |
| : "cc", "memory"); |
| } |
| |
| void * |
| memset(void *s, int c, size_t n) |
| { |
| while (n) |
| ((char *)s)[--n] = c; |
| return s; |
| } |
| |
| inline void |
| memcpy_far(u16 d_seg, void *d_far, u16 s_seg, const void *s_far, size_t len) |
| { |
| SET_SEG(ES, d_seg); |
| u16 bkup_ds; |
| asm volatile( |
| "movw %%ds, %w0\n" |
| "movw %w4, %%ds\n" |
| "rep movsb (%%si),%%es:(%%di)\n" |
| "movw %w0, %%ds" |
| : "=&r"(bkup_ds), "+c"(len), "+S"(s_far), "+D"(d_far) |
| : "r"(s_seg) |
| : "cc", "memory"); |
| } |
| |
| // Memcpy that uses 4-byte accesses |
| void |
| memcpy4(void *d1, const void *s1, size_t len) |
| { |
| len /= 4; |
| asm volatile( |
| "rep movsl (%%esi),%%es:(%%edi)" |
| : "+c"(len), "+S"(s1), "+D"(d1) |
| : : "cc", "memory"); |
| } |
| |
| void * |
| memmove(void *d, const void *s, size_t len) |
| { |
| if (s >= d) |
| return memcpy(d, s, len); |
| |
| d += len-1; |
| s += len-1; |
| while (len--) { |
| *(char*)d = *(char*)s; |
| d--; |
| s--; |
| } |
| |
| return d; |
| } |
| |
| // Copy a string - truncating it if necessary. |
| char * |
| strtcpy(char *dest, const char *src, size_t len) |
| { |
| char *d = dest; |
| while (len-- && *src != '\0') |
| *d++ = *src++; |
| *d = '\0'; |
| return dest; |
| } |
| |
| // Wait for 'usec' microseconds with irqs enabled. |
| void |
| usleep(u32 usec) |
| { |
| struct bregs br; |
| memset(&br, 0, sizeof(br)); |
| br.ah = 0x86; |
| br.cx = usec >> 16; |
| br.dx = usec; |
| call16_int(0x15, &br); |
| } |
| |
| // See if a keystroke is pending in the keyboard buffer. |
| static int |
| check_for_keystroke() |
| { |
| struct bregs br; |
| memset(&br, 0, sizeof(br)); |
| br.ah = 1; |
| call16_int(0x16, &br); |
| return !(br.flags & F_ZF); |
| } |
| |
| // Return a keystroke - waiting forever if necessary. |
| static int |
| get_raw_keystroke() |
| { |
| struct bregs br; |
| memset(&br, 0, sizeof(br)); |
| call16_int(0x16, &br); |
| return br.ah; |
| } |
| |
| // Read a keystroke - waiting up to 'msec' milliseconds. |
| int |
| get_keystroke(int msec) |
| { |
| for (;;) { |
| if (check_for_keystroke()) |
| return get_raw_keystroke(); |
| if (msec <= 0) |
| return -1; |
| usleep(50*1000); |
| msec -= 50; |
| } |
| } |