buffer.c

/*
 * -----------------------------------------------------------------------------
 * "THE BEER-WARE LICENSE" (Revision 42):
 * <webmaster@flippeh.de> wrote this file. As long as you retain this notice you
 * can do whatever you want with this stuff. If we meet some day, and you think
 * this stuff is worth it, you can buy me a beer in return. Lukas Niederbremer.
 * -----------------------------------------------------------------------------
 * NBTx modifications by Arnoldo A. Barón.
 * -----------------------------------------------------------------------------
 */
#include "buffer.h"

#include <assert.h>
#include <stddef.h>
#include <stdlib.h>
#include <string.h>

#ifdef __GNUC__
#define likely(x)   __builtin_expect(!!(x), 1)
#define unlikely(x) __builtin_expect(  (x), 0)
#else
#define likely(x)   (x)
#define unlikely(x) (x)
#endif

static int lazy_init(struct buffer* b) {
  assert(b->data == NULL);

  size_t cap = 1024;

  *b = (struct buffer) {
      .data = malloc(cap),
      .len = 0,
      .cap = cap
  };

  if (unlikely(b->data == NULL))
    return 1;

  return 0;
}

void buffer_free(struct buffer* b) {
  assert(b);

  free(b->data);

  b->data = NULL;
  b->len = 0;
  b->cap = 0;
}

int buffer_reserve(struct buffer* b, size_t reserved_amount) {
  assert(b);

  if (unlikely(b->data == NULL) &&
      unlikely(lazy_init(b)))
    return 1;

  if (likely(b->cap >= reserved_amount))
    return 0;

  while (b->cap < reserved_amount)
    b->cap *= 2;

  unsigned char* temp = realloc(b->data, b->cap);

  if (unlikely(temp == NULL))
    return buffer_free(b), 1;

  b->data = temp;

  return 0;
}

int buffer_append(struct buffer* b, const void* data, size_t n) {
  assert(b);

  if (unlikely(b->data == NULL) &&
      unlikely(lazy_init(b)))
    return 1;

  if (unlikely(buffer_reserve(b, b->len + n)))
    return 1;

  memcpy(b->data + b->len, data, n);
  b->len += n;

  return 0;
}