//=========================================================================
#define PROGRAMMER "SOLUTIONS, Nofrills"
#define PROG_CODE  "soln"
#define COURSE     "ECE-1021"
#define YEAR       (2004)
#define TERM       "Spring"
#define SECTION    (0)
#define ASSIGNMENT "HW #7B"
#define REVISION   (0)
#define TITLE      "Research of WAV and DTMF"
#define SUBTITLE   "Last Modified on 14 APR 04"
#define EMAIL      "ece1021@eas.uccs.edu"
#define FILENAME   "07b0soln.txt"
//=========================================================================

//=========================================================================
// PROBLEM
//=========================================================================
//
// 1) Describe the basic format of a WAV file.
// 2) Describe the basics of Touch-Tone dailing.
// 3) Describe how a dialing signal would be stored in a WAV file.

//=========================================================================
// WAV Basics
//=========================================================================
//
// Source of information:
//
// http://www.borg.com/~jglatt/tech/wave.htm
// http://www.ringthis.com/dev/wave_format.htm
//
// A WAV file consists of "chunks". Each chunk starts with a four-byte
// series of ASCII characters that identifies the type of the chunk
// followed by a four-byte integer that give the remaining number of
// bytes in the chunk. In otherwords, the size is the total size of the
// chunk minus eight.
//
// All multi-byte values are stored in Intel Little Endian format.
//
// Three types of chunks in a basic WAV File:
//
// RIFF chunk  (aka, RIFF Header)
// fmt  chunk
// data chunk
//
// ============================
// RIFF chunk
// ============================
//
// 12 bytes:
//  4 bytes: ASCII codes for 'RIFF'
//  4 bytes: Size of file remaining (total file size - 8)
//  4 bytes: ASCII codes for 'WAVE' (Type of RIFF file)
//
// ============================
// fmt chunk
// ============================
//
// 24 bytes (minimum):
//  4 bytes: ASCII codes for 'fmt '  (note the ending space)
//  4 bytes: Size of chunk remaining (total chunk size - 8) (usually 16)
//  2 bytes: Wave type (uncompressed PCM = 0x01)
//  2 bytes: Number of channels
//  4 bytes: Sample Rate (sample frames per second)
//  4 bytes: Byte Rate (bytes per second that must be read from file)
//  2 bytes: Block alignment - bytes per sample frame
//  2 bytes: Bits per sample (usually 8,12,16)
//
// ============================
// data chunk
// ============================
//
//  4 bytes: ASCII codes for 'data'
//  4 bytes: Size of chunk remaining (total chunk size - 8)
//  X bytes: The actual data
//
//  The data is organized by Sample Frame. All of the data for the first
//  Sample Frame is first, then the next Sample Frame's data, and so on.
//
//  Within a Sample Frame, the data is presented in Channel Order.
//
//  The data for a sample occupies the smallest number of whole bytes
//  required to hold the number of bits and the bits are left justified
//  with any unused bits set to zero.
//
//  If there are eight or fewer bits per sample, then the value is stored
//  as an unsigned value. But if there are more than eight bits per sample,
//  the bits are stored as signed values.
//
// ============================
// Calculations
// ============================
//
//  The three pieces of information that will be in the TXT file header
//  for HW#8B are:
//
//  Number of channels (Channels)
//  Significant bits per sample (Bits)
//  Sample rate (samples per second) (SampleRate)
//
//  Given this information:
//
//  BytesPerSample = (Bits/8) + (0 < Bits%8) (integer division intended)
//  BlockAlign = Channels * BytesPerSample
//  ByteRate = BlockAlign * SampleRate
//
//  If the number of bits per sample is not evenly divisble by eight, then
//  we must take care of the required left justification. This can be done
//  by simply shifting the value to the left by the appropriate number of
//  bits and can be accomplished by:
//
//  BitsToShift = (8 - BITS%8)%8
//  datavalue >>= BitsToShift

//=========================================================================
// DTMF Basics
//=========================================================================
//
// Source of information:
// http://www.hut.fi/~then/mytexts/dtmf_generation.html
//
//                  1209 Hz 1336 Hz 1477 Hz 1633 Hz
//
//                           ABC     DEF
//    697 Hz          1       2       3       A
//
//                   GHI     JKL     MNO
//    770 Hz          4       5       6       B
//
//                   PRS     TUV     WXY
//    852 Hz          7       8       9       C
//
//                           oper
//    941 Hz          *       0       #       D
//
// If I want to generate the tones for the number five key, I need to
// generate a sinewave at 852 Hz and one at 1336 Hz and add them together.
//

//=========================================================================
// DTMF WAV File
//=========================================================================
//
// The basic approach to generating the file will be to get a string of
// digits (the phone number) from the user and to generate a set of data
// representing the DTMF tones for that string of digits. For each digit,
// there will be a short segment of silence, followed by data obtained
// from the addition of the appropriate pair of tones, follwed by another
// short period of silence.
//
// 1) TASK: Get phone number from User
// 2) TASK: Initialize the WAV File
// 2.1) TASK: Compute Values that must be exported
// 2.2) TASK: Output all values to file except actual data
// 3) TASK: Generate the sound data
// 3.1) LOOP: For each digit in the phone number
// 3.1.1) TASK: Generate the "front porch"
// 3.1.1.1) LOOP: For duration of "front porch"
// 3.1.1.1.1) OUT: Zero Signal to file
// 3.1.2) TASK: Generate the DTMF signal
// 3.1.2.1) TASK: Look up the HI frequency.
// 3.1.2.2) TASK: Look up the LO frequency.
// 3.1.2.3) LOOP: For duration of tone
// 3.1.2.3.1) SET: Value = Amplitude * (sine(HI*t) + sine(LO*t))
// 3.1.2.3.1) OUT: Value to file
// 3.1.3) TASK: Generate the "back porch"
// 3.1.3.1) LOOP: For duration of "back porch"
// 3.1.3.1.1) OUT: Zero Signal to file
// 4) TASK: Close WAV file and perform any other housekeeping tasks