Aegisub/aegisub/libmedia/cache/audio_ram.cpp

// Copyright (c) 2005-2006, Rodrigo Braz Monteiro, Fredrik Mellbin
// All rights reserved.
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// Aegisub Project http://www.aegisub.org/
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// $Id$

/// @file audio_provider_ram.cpp
/// @brief Caching audio provider using heap memory for backing
/// @ingroup audio_input
///

#include "config.h"

#include "audio_provider_ram.h"
#include "dialog_progress.h"
#include "frame_main.h"
#include "main.h"
#include "utils.h"


/// DOCME
#define CacheBits ((22))

/// DOCME
#define CacheBlockSize ((1 << CacheBits))

/// @brief Constructor 
/// @param source 
///
RAMAudioProvider::RAMAudioProvider(AudioProvider *src) {
	std::auto_ptr<AudioProvider> source(src);
	// Init
	blockcache = NULL;
	blockcount = 0;
	samples_native_endian = source->AreSamplesNativeEndian();

	// Allocate cache
	int64_t ssize = source->GetNumSamples() * source->GetBytesPerSample();
	blockcount = (ssize + CacheBlockSize - 1) >> CacheBits;
	blockcache = new char*[blockcount];
	for (int i = 0; i < blockcount; i++) {
		blockcache[i] = NULL;
	}

	// Allocate cache blocks
	try {
		for (int i = 0; i < blockcount; i++) {
			blockcache[i] = new char[std::min<size_t>(CacheBlockSize,ssize-i*CacheBlockSize)];
		}
	}
	catch (...) { 
		Clear();
		throw AudioOpenError("Couldn't open audio, not enough ram available.");
	}

	// Copy parameters
	bytes_per_sample = source->GetBytesPerSample();
	num_samples = source->GetNumSamples();
	channels = source->GetChannels();
	sample_rate = source->GetSampleRate();
	filename = source->GetFilename();

	// Start progress
	volatile bool canceled = false;
	DialogProgress *progress = new DialogProgress(AegisubApp::Get()->frame,_("Load audio"),&canceled,_("Reading into RAM"),0,source->GetNumSamples());
	progress->Show();
	progress->SetProgress(0,1);

	// Read cache
	int readsize = CacheBlockSize / source->GetBytesPerSample();
	for (int i=0;i<blockcount && !canceled; i++) {
		source->GetAudio((char*)blockcache[i],i*readsize, i == blockcount-1 ? (source->GetNumSamples() - i*readsize) : readsize);
		progress->SetProgress(i,blockcount-1);
	}

	// Clean up progress
	if (canceled) {
		Clear();
		throw agi::UserCancelException("Audio loading cancelled by user");
	}
	progress->Destroy();
}

/// @brief Destructor 
///
RAMAudioProvider::~RAMAudioProvider() {
	Clear();
}

/// @brief Clear 
///
void RAMAudioProvider::Clear() {
	// Free ram cache
	if (blockcache) {
		for (int i = 0; i < blockcount; i++) {
			delete [] blockcache[i];
		}
		delete [] blockcache;
	}
	blockcache = NULL;
	blockcount = 0;
}

/// @brief Get audio 
/// @param buf   
/// @param start 
/// @param count 
///
void RAMAudioProvider::GetAudio(void *buf, int64_t start, int64_t count) const {
	// Requested beyond the length of audio
	if (start+count > num_samples) {
		int64_t oldcount = count;
		count = num_samples-start;
		if (count < 0) count = 0;

		// Fill beyond with zero
		if (bytes_per_sample == 1) {
			char *temp = (char *) buf;
			for (int i=count;i<oldcount;i++) {
				temp[i] = 0;
			}
		}
		if (bytes_per_sample == 2) {
			short *temp = (short *) buf;
			for (int i=count;i<oldcount;i++) {
				temp[i] = 0;
			}
		}
	}

	if (count) {
		// Prepare copy
		char *charbuf = (char *)buf;
		int i = (start*bytes_per_sample) >> CacheBits;
		int start_offset = (start*bytes_per_sample) & (CacheBlockSize-1);
		int64_t bytesremaining = count*bytes_per_sample;
		
		// Copy
		while (bytesremaining) {
			int readsize = std::min<int>(bytesremaining, CacheBlockSize - start_offset); 

			memcpy(charbuf,(char *)(blockcache[i++]+start_offset),readsize);

			charbuf+=readsize;

			start_offset=0;
			bytesremaining-=readsize;
		}
	}
}