/*
*   memory.c
*       by Reisyukaku / Aurora Wright
*   Copyright (c) 2016 All Rights Reserved
*
*   Quick Search algorithm adapted from http://igm.univ-mlv.fr/~lecroq/string/node19.html#SECTION00190
*/

#include "memory.h"

void memcpy(void *dest, const void *src, u32 size){
    u8 *destc = (u8 *)dest;
    const u8 *srcc = (const u8 *)src;
    for(u32 i = 0; i < size; i++)
        destc[i] = srcc[i];
}

void memset(void *dest, int filler, u32 size){
    u8 *destc = (u8 *)dest;
    for(u32 i = 0; i < size; i++)
        destc[i] = (u8)filler;
}

void memset32(void *dest, u32 filler, u32 size){
    u32 *dest32 = (u32 *)dest;
    for (u32 i = 0; i < size / 4; i++)
        dest32[i] = filler;
}

int memcmp(const void *buf1, const void *buf2, u32 size){
    const u8 *buf1c = (const u8 *)buf1;
    const u8 *buf2c = (const u8 *)buf2;
    for(u32 i = 0; i < size; i++){
        int cmp = buf1c[i] - buf2c[i];
        if(cmp) return cmp;
    }
    return 0;
}

u8 *memsearch(u8 *startPos, const void *pattern, u32 size, u32 patternSize){
    const u8 *patternc = (const u8 *)pattern;

    //Preprocessing
    int table[256];

    for(u32 i = 0; i < 256; ++i)
        table[i] = patternSize + 1;
    for(u32 i = 0; i < patternSize; ++i)
        table[patternc[i]] = patternSize - i;

    //Searching
    u32 j = 0;

    while(j <= size - patternSize){
        if(memcmp(patternc, startPos + j, patternSize) == 0)
            return startPos + j;
        j += table[startPos[j + patternSize]];
    }

    return NULL;
}