Espresso/libc/string.c

#include <stdint.h>
#include <stddef.h>

#include "include/string.h"

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

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

int strncmp(const char *s1, const char *s2, size_t n)
{
    while (n--)
    {
        unsigned char c1 = (unsigned char)*s1++;
        unsigned char c2 = (unsigned char)*s2++;
        if (c1 != c2)
        {
            return c1 - c2;
        }
        if (c1 == '\0')
        {
            break;
        }
    }
    return 0;
}

char* strcpy(char *dst, const char *src)
{
  char *ret = dst;
  while ((*dst++ = *src++) != 0);
  return ret;
}

char* strncpy(char *dest, const char *src, uint32_t n)
{
    uint32_t i = 0;
    for (; i < n && src[i]; ++i)
    {
        dest[i] = src[i];
    }

    for (; i < n; ++i)
    {
        dest[i] = '\0';
    }

    return dest;
}

char* strcat(char *dest, const char *src)
{
    char *end = dest + strlen(dest);
    while (*src)
    {
        *end++ = *src++;
    }
  
    *end = '\0';
    return dest;
}


/*char* strdup(const char* s)
{
    if (!s)
    {
        return NULL;
    }

    size_t len = strlen(s);
    char* copy = (char*)malloc(len + 1);

    if (!copy)
    {
        return NULL;
    }

    memcpy(copy, s, len);
    copy[len] = '\0';

    return copy;
}*/

void* memset(void* dst, int c, size_t n)
{
    unsigned char* temp = (unsigned char*) dst;
    unsigned char val = (unsigned char) c;

    for (size_t i = 0; i < n; i++)
    {
        temp[i] = val;
    }

    return dst;
}


void* memcpy(void *dst, const void *src, uint32_t n)
{
    char *d = dst;
    const char *s = src;
    while (n--)
    {
        *d++ = *s++;
    }
  
    return dst;
}