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// String manipulation functions.
//
// Copyright (C) 2008-2013 Kevin O'Connor <kevin@koconnor.net>
//
// This file may be distributed under the terms of the GNU LGPLv3 license.
#include "util.h" // yield
#include "string.h" // memcpy
#include "farptr.h" // SET_SEG
/****************************************************************
* String ops
****************************************************************/
// 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), "m" (__segment_ES)
: "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), "m" (__segment_ES)
: "cc", "memory");
}
void *
memset(void *s, int c, size_t n)
{
while (n)
((char *)s)[--n] = c;
return s;
}
void memset_fl(void *ptr, u8 val, size_t size)
{
if (MODESEGMENT)
memset_far(FLATPTR_TO_SEG(ptr), (void*)(FLATPTR_TO_OFFSET(ptr)),
val, size);
else
memset(ptr, val, size);
}
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), "m" (__segment_ES)
: "cc", "memory");
}
inline void
memcpy_fl(void *d_fl, const void *s_fl, size_t len)
{
if (MODESEGMENT)
memcpy_far(FLATPTR_TO_SEG(d_fl), (void*)FLATPTR_TO_OFFSET(d_fl)
, FLATPTR_TO_SEG(s_fl), (void*)FLATPTR_TO_OFFSET(s_fl)
, len);
else
memcpy(d_fl, s_fl, len);
}
void *
#undef memcpy
memcpy(void *d1, const void *s1, size_t len)
#if MODESEGMENT == 0
#define memcpy __builtin_memcpy
#endif
{
SET_SEG(ES, GET_SEG(SS));
void *d = d1;
if (((u32)d1 | (u32)s1 | len) & 3) {
// non-aligned memcpy
asm volatile(
"rep movsb (%%esi),%%es:(%%edi)"
: "+c"(len), "+S"(s1), "+D"(d)
: "m" (__segment_ES) : "cc", "memory");
return d1;
}
// Common case - use 4-byte copy
len /= 4;
asm volatile(
"rep movsl (%%esi),%%es:(%%edi)"
: "+c"(len), "+S"(s1), "+D"(d)
: "m" (__segment_ES) : "cc", "memory");
return d1;
}
// Copy to/from memory mapped IO. IO mem is very slow, so yield
// periodically.
void
iomemcpy(void *d, const void *s, u32 len)
{
ASSERT32FLAT();
yield();
while (len > 3) {
u32 copylen = len;
if (copylen > 2048)
copylen = 2048;
copylen /= 4;
len -= copylen * 4;
asm volatile(
"rep movsl (%%esi),%%es:(%%edi)"
: "+c"(copylen), "+S"(s), "+D"(d)
: : "cc", "memory");
yield();
}
if (len)
// Copy any remaining bytes.
memcpy(d, s, len);
}
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;
}
// locate first occurance of character c in the string s
char *
strchr(const char *s, int c)
{
for (; *s; s++)
if (*s == c)
return (char*)s;
return NULL;
}
// Remove any trailing blank characters (spaces, new lines, carriage returns)
void
nullTrailingSpace(char *buf)
{
int len = strlen(buf);
char *end = &buf[len-1];
while (end >= buf && *end <= ' ')
*(end--) = '\0';
}
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