--[[
   * ReaScript Name: Create WAVE file from array of numbers
   * Lua script for Cockos REAPER
   * Author: EUGEN27771
   * Author URI: http://forum.cockos.com/member.php?u=50462
   * Licence: GPL v3
   * Version: 1.0
  ]]

function Create_Wave_File(FilePath, buf, audioFormat, nchans, srate, bitspersample)
  if not (FilePath and buf and audioFormat and nchans and srate and bitspersample) then return reaper.MB("No data!","Info",0) end
  ----------------------------------------------------------
  local Pfmt --------------- Pack format -------------------
  if     audioFormat==3 and bitspersample==32 then Pfmt = "f"        -- 32 FP
  elseif audioFormat==3 and bitspersample==64 then Pfmt = "d"        -- 64 FP
  --elseif audioFormat==1 and bitspersample==24 then Pfmt = "i3"     -- 24 will be added in next version, don't use it now!
  --elseif audioFormat==1 and bitspersample==16 then Pfmt = "i2"     -- 16 will be added in next version, don't use it now! 
  else return reaper.MB( "Not supported format(32,64 bit, format 3 need!) !","Info",0) -- If format not supported
  end
  ----------------------------------------------------------
  local numSamples = #buf -- numSamples -------------------- 
  if numSamples<2 then return reaper.MB( "numSamples < 2","Info",0) end -- If numSamples < 2
  local data_ChunkDataSize = numSamples * nchans * bitspersample/8      -- Calculate data_ChunkDataSize!
  -----------------------------------------------------------------------------------------------------------------
  -- RIFF_Chunk =  RIFF_ChunkID, RIFF_chunkSize, RIFF_Type --------------------------------------------------------
  -----------------------------------------------------------------------------------------------------------------
    local RIFF_Chunk, RIFF_ChunkID, RIFF_chunkSize, RIFF_Type 
    RIFF_ChunkID   = "RIFF"
    RIFF_chunkSize = 36 + data_ChunkDataSize  -- 4 + (8+fmt_ChunkDataSize) + (8+data_ChunkDataSize)
    RIFF_Type      = "WAVE"
    RIFF_Chunk = string.pack("<c4 I4 c4",
                              RIFF_ChunkID,
                              RIFF_chunkSize,
                              RIFF_Type)  --------------------------------------------->>> Pack RIFF
  -----------------------------------------------------------------------------------------------------------------
  -- fmt_Chunk = fmt_ChunkID, fmt_ChunkDataSize, audioFormat, nchans, srate, byterate, blockalign, bitspersample --
  -----------------------------------------------------------------------------------------------------------------
    local fmt_Chunk, fmt_ChunkID, fmt_ChunkDataSize, byterate, blockalign
    fmt_ChunkID       = "fmt "
    fmt_ChunkDataSize = 16 
    byterate          = srate * nchans * bitspersample/8
    blockalign        = nchans * bitspersample/8
    fmt_Chunk  = string.pack("< c4 I4 I2 I2 I4 I4 I2 I2",
                              fmt_ChunkID,
                              fmt_ChunkDataSize,
                              audioFormat,
                              nchans,
                              srate,
                              byterate,
                              blockalign,
                              bitspersample)  ----------------------------------------->>> Pack fmt
  -----------------------------------------------------------------------------------------------------------------
  -- data_Chunk  =  data_ChunkID, data_ChunkDataSize, Data(bytes) - is written to a file later --------------------
  -----------------------------------------------------------------------------------------------------------------
    local data_Chunk, data_ChunkID
    data_ChunkID = "data"
    data_Chunk = string.pack("< c4 I4",
                              data_ChunkID,
                              data_ChunkDataSize)  ------------------------------------>>> Pack data(ID,size only)
  
  -----------------------------------------------------------------------------------------------------------------
  -- Pack data(samples) and Write to File -------------------------------------------------------------------------
  -----------------------------------------------------------------------------------------------------------------
    local file = io.open(FilePath,"wb")  -- Open file in "wb"
    if not file then return reaper.MB("File not aviable!","Info",0) end -- If file not aviable
      ---------------------------------------------------
      -- Pack values(samples), using Pfmt  --------------
      ---------------------------------------------------
      --[[ You can use simple version: for i=1, numSamples do Data_buf[i] = string.pack(Pfmt, buf[i] ) end
           But it is very slower, it is checked. Much faster packing blocks!!! ]]--
      ---------------------------------------------------
      local n = 1024                              -- Block size for packing(it can be changed)
      local rest = numSamples % n                 -- Rest, remainder of the division
      local Pfmt_str = "<" .. string.rep(Pfmt, n) -- Pack format string, for full blocks
      local Data_buf = {}
      -- Pack full blocks --------------
      local b = 1
      for i = 1, numSamples-rest, n do
          Data_buf[b] = string.pack(Pfmt_str, table.unpack( buf, i, i+n-1 ) ) ------------------->>>  Pack samples(Blocks)
          b = b+1
      end
      -- Pack rest ---------------------
      Pfmt_str = "<" .. string.rep(Pfmt, rest)    -- Pack format string, for rest
      Data_buf[b] = string.pack(Pfmt_str, table.unpack( buf, numSamples-rest+1, numSamples ) ) -->>>  Pack samples(Rest)
  
  -------------------------------------------------------
  -- Write Data to file ---------------------------------
  -------------------------------------------------------
  file:write(RIFF_Chunk,fmt_Chunk,data_Chunk, table.concat(Data_buf) ) ---------------->>>  Write All to File
  file:close()
 return true
end

----------------------------
----------------------------
--[[-- Simple Test(generate sine wave) --
FilePath = "C:\\Users\\EUGEN\\Desktop\\Test.wav" -- Choose your path !!!
--------
function Gen_Sine(Freq,srate,duration)
  if not Freq then return end
  Freq = math.min(math.max(Freq,10),22050)
  local buf = {}
  local Two_Pi = 2*math.pi 
  local adj = Two_Pi/srate * Freq
  local pos = 0
  -- gen sine --------------
    for i=1, srate*duration*2, 2 do 
        tone = math.sin(pos)
        buf[i]   = tone
        buf[i+1] = tone
        pos = pos+adj
        if pos>=Two_Pi then pos = pos-Two_Pi end
    end
  return buf
end
------------------------------------
------------------------------------
local start_time = reaper.time_precise()                        -- start time_test
local buf = Gen_Sine(440, 44100, 60*5)
reaper.ShowConsoleMsg("Generate time = ".. reaper.time_precise()-start_time .. '\n') -- generate time_test
----------------
local start_time = reaper.time_precise()                        -- start time_test
Create_Wave_File(FilePath, buf, 3, 2, 44100, 32)
reaper.ShowConsoleMsg("Create file time = ".. reaper.time_precise()-start_time .. '\n') -- create file time_test
--]]