/* vim: set ft=objc fenc=utf-8 sw=2 ts=2 et: */
/*
 *  DOUAudioStreamer - A Core Audio based streaming audio player for iOS/Mac:
 *
 *      https://github.com/douban/DOUAudioStreamer
 *
 *  Copyright 2013-2016 Douban Inc.  All rights reserved.
 *
 *  Use and distribution licensed under the BSD license.  See
 *  the LICENSE file for full text.
 *
 *  Authors:
 *      Chongyu Zhu <i@lembacon.com>
 *
 */

#import "DOUAudioLPCM.h"
#include <libkern/OSAtomic.h>

typedef struct data_segment {
  void *bytes;
  NSUInteger length;
  struct data_segment *next;
} data_segment;

@interface DOUAudioLPCM () {
@private
  data_segment *_segments;
  BOOL _end;
  OSSpinLock _lock;
}
@end

@implementation DOUAudioLPCM

@synthesize end = _end;

- (id)init
{
  self = [super init];
  if (self) {
    _lock = OS_SPINLOCK_INIT;
  }

  return self;
}

- (void)dealloc
{
  while (_segments != NULL) {
    data_segment *next = _segments->next;
    free(_segments);
    _segments = next;
  }
}

- (void)setEnd:(BOOL)end
{
  OSSpinLockLock(&_lock);
  if (end && !_end) {
    _end = YES;
  }
  OSSpinLockUnlock(&_lock);
}

- (BOOL)readBytes:(void **)bytes length:(NSUInteger *)length
{
  *bytes = NULL;
  *length = 0;

  OSSpinLockLock(&_lock);

  if (_end && _segments == NULL) {
    OSSpinLockUnlock(&_lock);
    return NO;
  }

  if (_segments != NULL) {
    *length = _segments->length;
    *bytes = malloc(*length);
    memcpy(*bytes, _segments->bytes, *length);

    data_segment *next = _segments->next;
    free(_segments);
    _segments = next;
  }

  OSSpinLockUnlock(&_lock);

  return YES;
}

- (void)writeBytes:(const void *)bytes length:(NSUInteger)length
{
  OSSpinLockLock(&_lock);

  if (_end) {
    OSSpinLockUnlock(&_lock);
    return;
  }

  if (bytes == NULL || length == 0) {
    OSSpinLockUnlock(&_lock);
    return;
  }

  data_segment *segment = (data_segment *)malloc(sizeof(data_segment) + length);
  segment->bytes = segment + 1;
  segment->length = length;
  segment->next = NULL;
  memcpy(segment->bytes, bytes, length);

  data_segment **link = &_segments;
  while (*link != NULL) {
    data_segment *current = *link;
    link = &current->next;
  }

  *link = segment;

  OSSpinLockUnlock(&_lock);
}

@end