alloc.c

来自「浙江大学编译原理课程设计源代码,高等院校计算机专业」· C语言 代码 · 共 55 行

#include "common.h"

struct block
{
    struct block *next;
    char *limit;
    char *avail;
};
union align {
    long l;
    char *p;
    double d;
    int (*f)(void);
};
union header {
    struct block b;
    union align a;
};

union header *arena[LASTARENA];

void *allocate(unsigned long n, unsigned a)
{
    union header *new = malloc(sizeof *new + n);

    assert(a < NELEMS(arena));
    if (new == NULL)
    {
        fprintf(stderr, "insufficient memory\n");
        exit(1);
    }
    new->b.next = (void *)arena[a];
    arena[a] = new;
    return new + 1;
}

void deallocate(unsigned a)
{
    union header *p, *q;

    assert(a < NELEMS(arena));
    for (p = arena[a]; p; p = q)
    {
        q = (void *)p->b.next;
        free(p);
    }
    arena[a] = NULL;
}

void *newarray(unsigned long m, unsigned long n, unsigned a)
{
    return allocate(m*n, a);
}