string.cpp

module;
#include <cstdint>
#include <cstddef>
#include <algorithm>

module string;

extern "C" {
void *memcpy(void *dest, const void *src, size_t n) {
  uint8_t *d = (uint8_t *)dest;
  uint8_t *s = (uint8_t *)src;
  while(n--) *d++ = *s++;
  return dest;
}

bool memzero(const void *s, size_t n) {
  const char *c = (const char *)s;
  for (size_t i = 0; i < n; ++i) {
    if (c[i] != 0) return false;
  }
  return true;
}

void *memchr(const void *s, int c, size_t n) {
  const unsigned char *p = (const unsigned char *)s;
  while (n--) {
    if (*p == (unsigned char)c) return (void *)p;
    p++;
  }
  return nullptr;
}

void *memset(void *s, int c, size_t n) {
  uint8_t *d = (uint8_t *)s;
  while(n--) *d++ = c;
  return s;
}

int strcmp(const char *s1, const char *s2) {
  while (*s1 && (*s1 == *s2)) {
    s1++;
    s2++;
  }
  return *(const unsigned char *)s1 - *(const unsigned char *)s2;
}

int memcmp(const void *s1, const void *s2, size_t n) {
  const unsigned char *t1 = (const unsigned char *)s1;
  const unsigned char *t2 = (const unsigned char *)s2;
  while ((*t1 == *t2)) {
    t1++;
    t2++;
    n--;
  }
  if (n == 0) return 0;
  return *t1 - *t2;
}
int strncmp(const char *s1, const char *s2, size_t n) {
  while (n && *s1 && (*s1 == *s2)) {
    s1++;
    s2++;
    n--;
  }
  if (n == 0) return 0;
  return *(const unsigned char *)s1 - *(const unsigned char *)s2;
}

char *strncpy(char *dest, const char *src, size_t n) {
  char *d = dest;
  while (n > 0 && *src != '\0') {
    *d++ = *src++;
    n--;
  }
  while (n > 0) {
    *d++ = '\0';
    n--;
  }
  return dest;
}

size_t strlen(const char *s) {
  size_t len = 0;
  while (*s++) len++;
  return len;
}
}