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// 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" // 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"
#else
"calll __call16_from32\n"
#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\n"
: "+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"
"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();
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\n"
: "+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);
}
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\n"
: "=&r"(bkup_ds), "+c"(len), "+S"(s_far), "+D"(d_far)
: "r"(s_seg)
: "cc", "memory");
}
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;
}
// 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;
}
}
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