////////////////////////////////////////////////////////////////////////////
//			     **** WAVPACK ****				  //
//		    Hybrid Lossless Wavefile Compressor			  //
//		Copyright (c) 1998 - 2004 Conifer Software.		  //
//			    All Rights Reserved.			  //
//      Distributed under the BSD Software License (see license.txt)      //
////////////////////////////////////////////////////////////////////////////

// wputils.c

// This module provides a high-level interface for decoding WavPack 4.0 audio
// streams and files. WavPack data is read with a stream reading callback. No
// direct seeking is provided for, but it is possible to start decoding
// anywhere in a WavPack stream. In this case, WavPack will be able to provide
// the sample-accurate position when it synchs with the data and begins
// decoding.

#include "wavpack.h"

#include <string.h>

static void strcpy_loc (char *dst, char *src) { while (*src) *dst++ = *src++; *dst = 0; }

///////////////////////////// local table storage ////////////////////////////

const ulong sample_rates [] = { 6000, 8000, 9600, 11025, 12000, 16000, 22050,
    24000, 32000, 44100, 48000, 64000, 88200, 96000, 192000 };

///////////////////////////// executable code ////////////////////////////////

static ulong read_next_header (read_stream infile, WavpackHeader *wphdr);
	
// This function reads data from the specified stream in search of a valid
// WavPack 4.0 audio block. If this fails in 1 megabyte (or an invalid or
// unsupported WavPack block is encountered) then an appropriate message is
// copied to "error" and NULL is returned, otherwise a pointer to a
// WavpackContext structure is returned (which is used to call all other
// functions in this module). This can be initiated at the beginning of a
// WavPack file, or anywhere inside a WavPack file. To determine the exact
// position within the file use WavpackGetSampleIndex(). For demonstration
// purposes this uses a single static copy of the WavpackContext structure,
// so obviously it cannot be used for more than one file at a time. Also,
// this function will not handle "correction" files, plays only the first
// two channels of multi-channel files, and is limited in resolution in some
// large integer or floating point files (but always provides at least 24 bits
// of resolution).

static WavpackContext wpc IDATA_ATTR;

WavpackContext *WavpackOpenFileInput (read_stream infile, char *error)
{
    WavpackStream *wps = &wpc.stream;
    ulong bcount;

    CLEAR (wpc);
    wpc.infile = infile;
    wpc.total_samples = (ulong) -1;
    wpc.norm_offset = 0;
    wpc.open_flags = 0;

    // open the source file for reading and store the size

    while (!wps->wphdr.block_samples) {

	bcount = read_next_header (wpc.infile, &wps->wphdr);

	if (bcount == (ulong) -1) {
	    strcpy_loc (error, "invalid WavPack file!");
	    return NULL;
	}

	if ((wps->wphdr.flags & UNKNOWN_FLAGS) || wps->wphdr.version < 0x402 || wps->wphdr.version > 0x40f) {
	    strcpy_loc (error, "invalid WavPack file!");
	    return NULL;
	}

	if (wps->wphdr.block_samples && wps->wphdr.total_samples != (ulong) -1)
	    wpc.total_samples = wps->wphdr.total_samples;

	if (!unpack_init (&wpc)) {
	    strcpy_loc (error, wpc.error_message [0] ? wpc.error_message :
		"invalid WavPack file!");

	    return NULL;
	}
    }

    wpc.config.flags &= ~0xff;
    wpc.config.flags |= wps->wphdr.flags & 0xff;
    wpc.config.bytes_per_sample = (wps->wphdr.flags & BYTES_STORED) + 1;
    wpc.config.float_norm_exp = wps->float_norm_exp;

    wpc.config.bits_per_sample = (wpc.config.bytes_per_sample * 8) - 
	((wps->wphdr.flags & SHIFT_MASK) >> SHIFT_LSB);

    if (!wpc.config.sample_rate) {
	if (!wps || !wps->wphdr.block_samples || (wps->wphdr.flags & SRATE_MASK) == SRATE_MASK)
	    wpc.config.sample_rate = 44100;
	else
	    wpc.config.sample_rate = sample_rates [(wps->wphdr.flags & SRATE_MASK) >> SRATE_LSB];
    }

    if (!wpc.config.num_channels) {
	wpc.config.num_channels = (wps->wphdr.flags & MONO_FLAG) ? 1 : 2;
	wpc.config.channel_mask = 0x5 - wpc.config.num_channels;
    }

    if (!(wps->wphdr.flags & FINAL_BLOCK))
	wpc.reduced_channels = (wps->wphdr.flags & MONO_FLAG) ? 1 : 2;

    return &wpc;
}

// This function obtains general information about an open file and returns
// a mask with the following bit values:

// MODE_LOSSLESS:  file is lossless (pure lossless only)
// MODE_HYBRID:  file is hybrid mode (lossy part only)
// MODE_FLOAT:  audio data is 32-bit ieee floating point
// MODE_HIGH:  file was created in "high" mode (information only)
// MODE_FAST:  file was created in "fast" mode (information only)

int WavpackGetMode (WavpackContext *wpc)
{
    int mode = 0;

    if (wpc) {
	if (wpc->config.flags & CONFIG_HYBRID_FLAG)
	    mode |= MODE_HYBRID;
	else if (!(wpc->config.flags & CONFIG_LOSSY_MODE))
	    mode |= MODE_LOSSLESS;

	if (wpc->lossy_blocks)
	    mode &= ~MODE_LOSSLESS;

	if (wpc->config.flags & CONFIG_FLOAT_DATA)
	    mode |= MODE_FLOAT;

	if (wpc->config.flags & CONFIG_HIGH_FLAG)
	    mode |= MODE_HIGH;

	if (wpc->config.flags & CONFIG_FAST_FLAG)
	    mode |= MODE_FAST;
    }

    return mode;
}

// Unpack the specified number of samples from the current file position.
// Note that "samples" here refers to "complete" samples, which would be
// 2 longs for stereo files. The audio data is returned right-justified in
// 32-bit longs in the endian mode native to the executing processor. So,
// if the original data was 16-bit, then the values returned would be
// +/-32k. Floating point data can also be returned if the source was
// floating point data (and this is normalized to +/-1.0). The actual number
// of samples unpacked is returned, which should be equal to the number
// requested unless the end of fle is encountered or an error occurs.

ulong WavpackUnpackSamples (WavpackContext *wpc, long *buffer, ulong samples)
{
    WavpackStream *wps = &wpc->stream;
    ulong bcount, samples_unpacked = 0, samples_to_unpack;
    int num_channels = wpc->config.num_channels;

    while (samples) {
	if (!wps->wphdr.block_samples || !(wps->wphdr.flags & INITIAL_BLOCK) ||
	    wps->sample_index >= wps->wphdr.block_index + wps->wphdr.block_samples) {
		bcount = read_next_header (wpc->infile, &wps->wphdr);

		if (bcount == (ulong) -1)
		    break;

		if (wps->wphdr.version < 0x402 || wps->wphdr.version > 0x40f) {
		    strcpy_loc (wpc->error_message, "invalid WavPack file!");
		    break;
		}

		if (!wps->wphdr.block_samples || wps->sample_index == wps->wphdr.block_index)
		    if (!unpack_init (wpc))
			break;
	}

	if (!wps->wphdr.block_samples || !(wps->wphdr.flags & INITIAL_BLOCK) ||
	    wps->sample_index >= wps->wphdr.block_index + wps->wphdr.block_samples)
		continue;

	if (wps->sample_index < wps->wphdr.block_index) {
	    samples_to_unpack = wps->wphdr.block_index - wps->sample_index;

	    if (samples_to_unpack > samples)
		samples_to_unpack = samples;

	    wps->sample_index += samples_to_unpack;
	    samples_unpacked += samples_to_unpack;
	    samples -= samples_to_unpack;

	    if (wpc->reduced_channels)
		samples_to_unpack *= wpc->reduced_channels;
	    else
		samples_to_unpack *= num_channels;

	    while (samples_to_unpack--)
		*buffer++ = 0;

	    continue;
	}

	samples_to_unpack = wps->wphdr.block_index + wps->wphdr.block_samples - wps->sample_index;

	if (samples_to_unpack > samples)
	    samples_to_unpack = samples;

	unpack_samples (wpc, buffer, samples_to_unpack);

	if (wpc->reduced_channels)
	    buffer += samples_to_unpack * wpc->reduced_channels;
	else
	    buffer += samples_to_unpack * num_channels;

	samples_unpacked += samples_to_unpack;
	samples -= samples_to_unpack;

	if (wps->sample_index == wps->wphdr.block_index + wps->wphdr.block_samples) {
	    if (check_crc_error (wpc))
		wpc->crc_errors++;
	}

	if (wps->sample_index == wpc->total_samples)
	    break;
    }

    return samples_unpacked;
}

// Get total number of samples contained in the WavPack file, or -1 if unknown

ulong WavpackGetNumSamples (WavpackContext *wpc)
{
    return wpc ? wpc->total_samples : (ulong) -1;
}

// Get the current sample index position, or -1 if unknown

ulong WavpackGetSampleIndex (WavpackContext *wpc)
{
    if (wpc)
	return wpc->stream.sample_index;

    return (ulong) -1;
}

// Get the number of errors encountered so far

int WavpackGetNumErrors (WavpackContext *wpc)
{
    return wpc ? wpc->crc_errors : 0;
}

// return TRUE if any uncorrected lossy blocks were actually written or read

int WavpackLossyBlocks (WavpackContext *wpc)
{
    return wpc ? wpc->lossy_blocks : 0;
}

// Returns the sample rate of the specified WavPack file

ulong WavpackGetSampleRate (WavpackContext *wpc)
{
    return wpc ? wpc->config.sample_rate : 44100;
}

// Returns the number of channels of the specified WavPack file. Note that
// this is the actual number of channels contained in the file, but this
// version can only decode the first two.

int WavpackGetNumChannels (WavpackContext *wpc)
{
    return wpc ? wpc->config.num_channels : 2;
}

// Returns the actual number of valid bits per sample contained in the
// original file, which may or may not be a multiple of 8. Floating data
// always has 32 bits, integers may be from 1 to 32 bits each. When this
// value is not a multiple of 8, then the "extra" bits are located in the
// LSBs of the results. That is, values are right justified when unpacked
// into longs, but are left justified in the number of bytes used by the
// original data.

int WavpackGetBitsPerSample (WavpackContext *wpc)
{
    return wpc ? wpc->config.bits_per_sample : 16;
}

// Returns the number of bytes used for each sample (1 to 4) in the original
// file. This is required information for the user of this module because the
// audio data is returned in the LOWER bytes of the long buffer and must be
// left-shifted 8, 16, or 24 bits if normalized longs are required.

int WavpackGetBytesPerSample (WavpackContext *wpc)
{
    return wpc ? wpc->config.bytes_per_sample : 2;
}

// This function will return the actual number of channels decoded from the
// file (which may or may not be less than the actual number of channels, but
// will always be 1 or 2). Normally, this will be the front left and right
// channels of a multi-channel file.

int WavpackGetReducedChannels (WavpackContext *wpc)
{
    if (wpc)
	return wpc->reduced_channels ? wpc->reduced_channels : wpc->config.num_channels;
    else
	return 2;
}

// Read from current file position until a valid 32-byte WavPack 4.0 header is
// found and read into the specified pointer. The number of bytes skipped is
// returned. If no WavPack header is found within 1 meg, then a -1 is returned
// to indicate the error. No additional bytes are read past the header and it
// is returned in the processor's native endian mode. Seeking is not required.

static ulong read_next_header (read_stream infile, WavpackHeader *wphdr)
{
    char buffer [sizeof (*wphdr)], *sp = buffer + sizeof (*wphdr), *ep = sp;
    ulong bytes_skipped = 0;
    int bleft;

    while (1) {
	if (sp < ep) {
	    bleft = ep - sp;
	    memcpy (buffer, sp, bleft);
	}
	else
	    bleft = 0;

	if (infile (buffer + bleft, sizeof (*wphdr) - bleft) != (long) sizeof (*wphdr) - bleft)
	    return -1;

	sp = buffer;

	if (*sp++ == 'w' && *sp == 'v' && *++sp == 'p' && *++sp == 'k' &&
	    !(*++sp & 1) && sp [2] < 16 && !sp [3] && sp [5] == 4 && sp [4] >= 2 && sp [4] <= 0xf) {
		memcpy (wphdr, buffer, sizeof (*wphdr));
		little_endian_to_native (wphdr, WavpackHeaderFormat);
		return bytes_skipped;
	    }

	while (sp < ep && *sp != 'w')
	    sp++;

	if ((bytes_skipped += sp - buffer) > 1024 * 1024)
	    return -1;
    }
}