membuf.c

Go to the documentation of this file.

 
#include "util.h"
#define LELY_UTIL_MEMBUF_INLINE extern inline
#include <lely/util/errnum.h>
#include <lely/util/membuf.h>
 
#include <assert.h>
#include <stdlib.h>
 
#ifndef LELY_MEMBUF_SIZE
#define LELY_MEMBUF_SIZE 16
#endif
 
void
membuf_fini(struct membuf *buf)
{
        assert(buf);
 
        free(buf->begin);
}
 
size_t
membuf_reserve(struct membuf *buf, size_t size)
{
        assert(buf);
 
        size_t capacity = membuf_capacity(buf);
        if (size <= capacity)
                return capacity;
 
        // The required size equals the size of the data already in the buffer,
        // plus the data to be added. To limit the number of allocations, we
        // keep doubling the size of the buffer until it is large enough.
        size_t buf_size = LELY_MEMBUF_SIZE;
        while (buf_size < membuf_size(buf) + size)
                buf_size *= 2;
 
        char *begin = realloc(buf->begin, buf_size);
        if (!begin) {
                set_errc(errno2c(errno));
                return 0;
        }
 
        buf->cur = begin + membuf_size(buf);
        buf->begin = begin;
        buf->end = buf->begin + buf_size;
 
        return membuf_capacity(buf);
}
 
void
membuf_flush(struct membuf *buf, size_t size)
{
        assert(buf);
 
        size = MIN(size, membuf_size(buf));
        if (size)
                memmove(buf->begin, buf->begin + size, membuf_size(buf) - size);
        buf->cur -= size;
}