jtortoise
2/8/2018 - 12:50 PM

STM32 C 简单粗暴的散列映射hashmap

C官方库虽然没有提供map库，但第三方库还是有一些挺不错的，用了几个后发现这些hashmap库对内存有一些要求，而针对STM32这种MCU，内存是最珍贵的资源了，基本都满足不了这些库的要求，就只能自己动手写一个简单粗暴的hashmap库满足自己的需求。

example.c
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#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>

#include "hashmap.h"

int main(void)
{
    int val[5] = {0, 1, 2, 3, 4};
    hashmap* map = HashmapInit(5);

    int i=0;
    for(;i<5; i++)
    {
        HashmapPut(map, i, (void*)(val+i));
    }

    int key = 0;
    for(; key<5; key++)
    {
        int *temp = (int*)HashmapGet(map, key);
        printf("%d->%d\n", key, *temp);
    }
    return 0;
}
hashmap.c
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#include "hashmap.h"

int HashForInt(hashmap* obj, int key)
{
    if(key < 0)
        return ((-key)%(obj->size));

    return (key%(obj->size));
}

hashmap* HashmapInit(int size)
{
    struct _hashmap_table* obj = (struct _hashmap_table*)malloc(sizeof(struct _hashmap_table));
    if(obj == NULL)
        return NULL;

    obj->size = size;
    obj->list = (struct _hashmap_node**)calloc(size, sizeof(struct _hashmap_node*));

    return obj;
}

void HashmapDestory(hashmap* obj)
{
    int i=0;
    //循环释放各对键值
    for(i=0; i<obj->size; i++)
    {
        if(obj->list[i] != NULL)
            free(obj->list[i]);
    }

    free(obj->list);
    free(obj);
}

void* HashmapPut(hashmap* obj, int key, void *value)
{
    int hash=0;
    struct _hashmap_node* node=NULL;

    if(obj == NULL)
        return NULL;

    hash = HashForInt(obj, key);
    if(obj->list[hash] != NULL)
        return NULL;

    node = (struct _hashmap_node*)malloc(sizeof(struct _hashmap_node));
    if(node == NULL)
        return NULL;

    node->key = key;
    node->value = value;

    obj->list[hash] = node;
    return (obj->list[hash]);
}

void* HashmapGet(hashmap* obj, int key)
{
    int hash = HashForInt(obj, key);
    struct _hashmap_node* node = obj->list[hash];
    if(node == NULL || node->key != key)
        return NULL;

    return node->value;
}
hashmap.h
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#ifndef __HASHMAP_H
#define __HASHMAP_H

#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>

typedef struct _hashmap_node
{
    void* value;
    int key;
}hashmap_node;

typedef struct _hashmap_table
{
    int size;
    struct _hashmap_node** list;
}hashmap;

int HashForInt(hashmap* obj, int key);

hashmap* HashmapInit(int size);
void HashmapDestory(hashmap* obj);

void* HashmapPut(hashmap* obj, int key, void *value);
void* HashmapGet(hashmap* obj, int key);


#endif //__HASHMAP_H