bytebuf.h

/**
 * MIT License
 * 
 * Copyright (c) 2018 leonardosnt <leonrdsnt@gmail.com>
 * 
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 * 
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

#ifndef bytebuf__h_
#define bytebuf__h_

#include <stdlib.h>
#include <string.h>
#include <stdint.h>
#include <stdbool.h>

#define CAN_WRITE(buf, size) (buf->offset + size <= buf->length)

/** 
 * Generate a function that looks like this:
 * 
 * bool bytebuf_write_float(bytebuf_t* buf, float value) {
 *   if (!CAN_WRITE(buf, sizeof(float))) {
 *     return false;
 *   }
 *   *((float*) (buf->data + buf->offset)) = value;
 *   buf->offset += sizeof(float);
 *   return true;
 * }
 */
#define WRITE_TEMPLATE(name_suffix, type)                      \
bool bytebuf_write_##name_suffix(bytebuf_t* buf, type value) { \
  if (!CAN_WRITE(buf, sizeof(type))) {                         \
    return false;                                              \
  }                                                            \
  *((type*) (buf->data + buf->offset)) = value;                \
  buf->offset += sizeof(type);                                 \
  return true;                                                 \
}

/** 
 * Generate a function that looks like this:
 * 
 * float bytebuf_read_float(bytebuf_t* buf) {
 *   float result = *((float*) (buf->data + buf->offset));
 *   buf->offset += sizeof(float);
 *   return result;
 * }
 */
#define READ_TEMPLATE(name_suffix, type)                    \
type bytebuf_read_##name_suffix(bytebuf_t* buf) {           \
  type result = *((type*) (buf->data + buf->offset));       \
  buf->offset += sizeof(type);                              \
  return result;                                            \
}

typedef struct {
  uint8_t* data;

  /* length of data */
  size_t length;

  /* current write/read offset */
  uint32_t offset;
} bytebuf_t;

bytebuf_t* bytebuf_wrap(uint8_t* data, size_t length) {
  bytebuf_t* buf = (bytebuf_t*) malloc(sizeof(bytebuf_t));
  buf->data = data;
  buf->length = length;
  buf->offset = 0;
  return buf;
}

/**
 * Alloc a new bytebuf and return it
 */
bytebuf_t* bytebuf_alloc(size_t size) {
  bytebuf_t* buf = (bytebuf_t*) malloc(sizeof(bytebuf_t));
  
  buf->data = (uint8_t*) malloc(size);
  buf->length = size;
  buf->offset = 0;

  return buf;
}

/**
 * Alloc a new bytebuf and fill its data with zeros
 */
bytebuf_t* bytebuf_calloc(size_t size) {
  bytebuf_t* buf = bytebuf_alloc(size);
  memset(buf->data, 0, size);
  return buf;
}

void bytebuf_free(bytebuf_t* buf) {
  free(buf->data);
  free(buf);
}

bool bytebuf_write(bytebuf_t* buf, char* data, size_t data_size) {
  if (!CAN_WRITE(buf, data_size)) {
    return false;
  }
  memcpy((buf->data + buf->offset), data, data_size);
  buf->offset += data_size;
  return true;
}

WRITE_TEMPLATE(i8, int8_t)     /* bool bytebuf_write_i8(bytebuf_t* buf, int8_t value);     */
WRITE_TEMPLATE(i16, int16_t)   /* bool bytebuf_write_i16(bytebuf_t* buf, int16_t value);   */
WRITE_TEMPLATE(i32, int32_t)   /* bool bytebuf_write_i32(bytebuf_t* buf, int32_t value);   */
WRITE_TEMPLATE(i64, int64_t)   /* bool bytebuf_write_i64(bytebuf_t* buf, int64_t value);   */
WRITE_TEMPLATE(float, float)   /* bool bytebuf_write_float(bytebuf_t* buf, float value);   */
WRITE_TEMPLATE(double, double) /* bool bytebuf_write_double(bytebuf_t* buf, double value); */

READ_TEMPLATE(i8, int8_t)      /* int8_t bytebuf_read_i8(bytebuf_t* buf);  */
READ_TEMPLATE(i16, int16_t)    /* int16_t bytebuf_read_i16(bytebuf_t* buf); */
READ_TEMPLATE(i32, int32_t)    /* int32_t bytebuf_read_i32(bytebuf_t* buf); */
READ_TEMPLATE(i64, int64_t)    /* int64_t bytebuf_read_i64(bytebuf_t* buf); */
READ_TEMPLATE(float, float)    /* float bytebuf_read_float(bytebuf_t* buf);   */
READ_TEMPLATE(double, double)  /* double bytebuf_read_double(bytebuf_t* buf);  */

#endif