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#include <string.h>
extern "C" void *memset(void *vdest, int64_t ch, size_t len)
{
// TODO: align to an 8-byte boundary
// Loop, storing 8 bytes every 3 instructions
long *ldest = reinterpret_cast<long *>(vdest);
if (len >= sizeof(long))
{
long lch = ch & 0xFF;
lch |= lch<<8;
lch |= lch<<16;
lch |= lch<<32;
size_t len8 = len / sizeof(long);
size_t i = len8;
do
{
ldest[--i] = lch;
}
while( i > 0 );
ldest += len8;
len -= len8 * sizeof(long);
}
// Loop, storing 1 byte every 3 instructions
char *cdest = reinterpret_cast<char *>(ldest);
while (len >= sizeof(char))
{
*cdest++ = ch;
len -= sizeof(char);
}
return vdest;
}
extern "C" void bzero(void *vdest, size_t len)
{
memset(vdest, 0, len);
}
extern "C" void *memcpy(void *vdest, const void *vsrc, size_t len)
{
// TODO: align to an 8-byte boundary?
// Loop, copying 8 bytes every 5 instructions (TODO: 8/4 should be possible)
long *ldest = reinterpret_cast<long *>(vdest);
const long *lsrc = reinterpret_cast<const long *>(vsrc);
while (len >= sizeof(long))
{
*ldest++ = *lsrc++;
len -= sizeof(long);
}
// Loop, copying 1 byte every 4 instructions
char *cdest = reinterpret_cast<char *>(ldest);
const char *csrc = reinterpret_cast<const char *>(lsrc);
for (size_t i = 0; i < len; ++i)
{
cdest[i] = csrc[i];
}
return vdest;
}
extern "C" void *memmove(void *vdest, const void *vsrc, size_t len)
{
// Copy first-to-last
if (vdest <= vsrc)
{
return memcpy(vdest,vsrc,len);
}
// Copy last-to-first (TO_DO: optimize)
char *dest = reinterpret_cast<char *>(vdest);
const char *src = reinterpret_cast<const char *>(vsrc);
for (size_t i = len; i > 0;)
{
--i;
dest[i] = src[i];
}
return vdest;
}
extern "C" int64_t memcmp(const void *p1, const void *p2, size_t len)
{
const char *c1 = reinterpret_cast<const char *>(p1);
const char *c2 = reinterpret_cast<const char *>(p2);
for (size_t i = 0; i < len; ++i)
{
long n = static_cast<long>(c1[i]) - static_cast<long>(c2[i]);
if (n != 0)
{
return n;
}
}
return 0;
}
extern "C" char* strcpy(char* d, const char* s)
{
char* d1 = d;
do
{
*d1 = *s;
if (*s == '\0') return d;
d1++; s++;
} while(1);
}
extern "C" int strcmp(const char* a, const char* b)
{
while((*a != '\0') && (*b != '\0'))
{
if (*a == *b)
{
a++; b++;
}
else
{
return (*a > *b) ? 1 : -1;
}
}
if (*a == *b)
return 0;
if (*a == '\0')
return -1;
else
return 1;
}
extern "C" size_t strlen(const char* a)
{
size_t length = 0;
while(*a++)
{
length++;
}
return length;
}
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