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path: root/kernel/src/klibc/string.cpp
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#include <cstdint>
#include <klibc/string.hpp>

void* klibc::memcpy(void *__restrict dest, const void *__restrict src, std::size_t n) {
    std::uint8_t *__restrict pdest = static_cast<std::uint8_t *__restrict>(dest);
    const std::uint8_t *__restrict psrc = static_cast<const std::uint8_t *__restrict>(src);

    for (std::size_t i = 0; i < n; i++) {
        pdest[i] = psrc[i];
    }

    return dest;
}

void* klibc::memset(void *s, int c, std::size_t n) {
    std::uint8_t *p = static_cast<std::uint8_t *>(s);

    for (std::size_t i = 0; i < n; i++) {
        p[i] = static_cast<uint8_t>(c);
    }

    return s;
}

void* klibc::memmove(void *dest, const void *src, std::size_t n) {
    std::uint8_t *pdest = static_cast<std::uint8_t *>(dest);
    const std::uint8_t *psrc = static_cast<const std::uint8_t *>(src);

    if (reinterpret_cast<std::uintptr_t>(src) > reinterpret_cast<std::uintptr_t>(dest)) {
        for (std::size_t i = 0; i < n; i++) {
            pdest[i] = psrc[i];
        }
    } else if (reinterpret_cast<std::uintptr_t>(src) < reinterpret_cast<std::uintptr_t>(dest)) {
        for (std::size_t i = n; i > 0; i--) {
            pdest[i-1] = psrc[i-1];
        }
    }

    return dest;
}

int klibc::memcmp(const void *s1, const void *s2, std::size_t n) {
    const std::uint8_t *p1 = static_cast<const std::uint8_t *>(s1);
    const std::uint8_t *p2 = static_cast<const std::uint8_t *>(s2);

    for (std::size_t i = 0; i < n; i++) {
        if (p1[i] != p2[i]) {
            return p1[i] < p2[i] ? -1 : 1;
        }
    }

    return 0;
}

int klibc::strlen(const char *str) {
    int len = 0;
    while (str[len] != '\0') {
        len++;
    }
    return len;
}