pk/memset.c


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#include <limits.h>
#include <string.h>

#if ULONG_MAX != 18446744073709551615UL && ULONG_MAX != 4294967295UL
# error need sizeof(long) == 4 or sizeof(long) == 8
#endif

void* memset(void* m, int ch, size_t s)
{
  size_t i;
  char* mem = (char*)m;
  long* lmem;

  if(s < sizeof(long))
  {
    for(i = 0; i < s; i++)
      mem[i] = ch;
    return m;
  }

  long l = ch & 0xFF;
  l = l | (l << 8);
  l = l | (l << 16);
  #if ULONG_MAX == 18446744073709551615UL
  l = l | (l << 32);
  #endif

  while((long)mem & (sizeof(long)-1))
    *mem++ = ch, s--;
  lmem = (long*)mem;

  for(i = 0; i+7 < s/sizeof(long); i += 8)
  {
    lmem[i+0] = l;
    lmem[i+1] = l;
    lmem[i+2] = l;
    lmem[i+3] = l;
    lmem[i+4] = l;
    lmem[i+5] = l;
    lmem[i+6] = l;
    lmem[i+7] = l;
  }
  lmem += i;
  s -= i*sizeof(long);

  for(i = 0; i < s/sizeof(long); i++)
    lmem[i] = l;
  lmem += i;
  s -= i*sizeof(long);

  mem = (char*)lmem;
  for(i = 0; i < s; i++)
    mem[i] = ch;

  return m;
}