blob: af5dbd3376f5f3fc2dd175233282fda67ddffea1 [file] [log] [blame]
// Misc utility functions.
//
// Copyright (C) 2008 Kevin O'Connor <kevin@koconnor.net>
//
// This file may be distributed under the terms of the GNU LGPLv3 license.
#include "util.h" // usleep
#include "bregs.h" // struct bregs
#include "config.h" // SEG_BIOS
#include "farptr.h" // GET_FARPTR
#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"
#else
"calll __call16_from32\n"
#endif
: "+a" (callregs), "+m" (*callregs)
:
: "ebx", "ecx", "edx", "esi", "edi", "ebp", "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\n"
: "+a" (callregs), "+m" (*callregs)
:
: "ebx", "ecx", "edx", "esi", "edi", "ebp", "cc", "memory");
}
inline void
__call16_int(struct bregs *callregs, u16 offset)
{
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"
"cld\n"
"cli\n"
: "+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();
u32 ebda_seg = get_ebda_seg();
u32 tmp;
asm volatile(
// Backup current %ss value.
"movl %%ss, %4\n"
// Copy ebda seg to %ss and %ds
"movl %3, %%ss\n"
"movl %3, %%ds\n"
// Backup %esp and set it to new value
"movl %%esp, %3\n"
"movl %5, %%esp\n"
// Call func
"calll %6\n"
// Restore segments and stack
"movl %3, %%esp\n"
"movl %4, %%ss\n"
"movl %4, %%ds\n"
: "+a" (eax), "+d" (edx), "+c" (ecx), "+r" (ebda_seg), "=r" (tmp)
: "i" (EBDA_OFFSET_TOP_STACK), "m" (*(u8*)func)
: "cc", "memory");
return eax;
}
// Sum the bytes in the specified area.
u8
checksum(u8 *far_data, u32 len)
{
u32 i;
u8 sum = 0;
for (i=0; i<len; i++)
sum += GET_FARPTR(far_data[i]);
return sum;
}
void *
memset(void *s, int c, size_t n)
{
while (n)
((char *)s)[--n] = c;
return s;
}
void *
memcpy_far(void *far_d1, const void *far_s1, size_t len)
{
u8 *d = far_d1;
u8 *s = (u8*)far_s1;
while (len--) {
SET_FARPTR(*d, GET_FARPTR(*s));
d++;
s++;
}
return far_d1;
}
void *
memcpy(void *d1, const void *s1, size_t len)
{
u8 *d = (u8*)d1, *s = (u8*)s1;
while (len--)
*d++ = *s++;
return d1;
}
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;
}