// Project: FLDEVOX by Xaby
// Created: 2017-04-06

/*  converted from C to AGK2 by Xaby aka Folker Linstedt

// Source: http://faculty.salina.k-state.edu/tim/software/vox/vox.html#the-standard
// by Tim Bower

/*  File: adpcm.c
    Description: Routines to convert 12 bit linear samples to the
       Dialogic or Oki ADPCM coding format.
       I copied the algorithms out of the book "PC Telephony - The
       complete guide to designing, building and programming systems
       using Dialogic and Related Hardware" by Bob Edgar. pg 272-276.

   Note: Edgar's book says that the second to last value is 1408; however,
 * The standard says it is 1411.
 * Changed on 1/17/2003.

*/


// show all errors
SetErrorMode(2)

// set window properties
SetWindowTitle( "FLDEVOX" )
SetWindowSize( 320, 200, 0 )

// set display properties
SetVirtualResolution( 320, 200 )
SetOrientationAllowed( 1, 1, 1, 1 )
SetSyncRate( 30, 0 ) // 30fps instead of 60 to save battery
UseNewDefaultFonts( 1 ) // since version 2.0.22 we can use nicer default fonts



Type adpcm_status
	last as integer // short -127..128
	step_index as integer // short -127..128	
EndType

Global coder_stat as adpcm_status // global, because no classes?

Function adpcm_init( stat as adpcm_status)
    stat.last = 0
    stat.step_index = 0
    
    coder_stat.last = 0 // only here because of global variable
    coder_stat.step_index = 0  // only here because of global variable  
EndFunction 

Global adpcm_step_size as integer[49] = [16, 17, 19, 21, 23, 25, 28, 31, 34, 37, 41, 45, 50, 55, 60, 66, 73, 80, 88, 97, 107, 118, 130, 143, 157, 173, 190, 209, 230, 253, 279, 307, 337, 371, 408, 449, 494, 544, 598, 658, 724, 796, 876, 963, 1060, 1166, 1282, 1411, 1552]

Function step_adjust(code as integer)
	value = 0
	select( code && 0x07 ) 
        case 0x00:
            value=-1
        endcase
        case 0x01:
            value=-1
         endcase
        case 0x02:
            value=-1
         endcase
        case 0x03:
            value=-1
         endcase
        case 0x04:
            value=2
        endcase
        case 0x05:
            value=4
        endcase
        case 0x06:
            value=6
        endcase
        case 0x07:
            value=8
        endcase
    endselect
	
	
Endfunction	value


/*
* Decode Linear to ADPCM
*/
function adpcm_decode( code as integer) // without global: function adpcm_decode( code as integer, stat as adpcm_status)
    diff as integer
    E as integer
    SS as integer
    samp as integer

    /* printf( "%x\t", code );
    */
    SS = adpcm_step_size[coder_stat.step_index] // stat.step_index without global
    E = SS/8
    if ( code && 0x01 )
        E = E+SS/4
    endif    
    if ( code && 0x02 )
        E =E+ SS/2
    endif   
    if ( code && 0x04 )
        E = E+SS
    endif    
    //  diff = (code & 0x08) ? -E : E;
    if (code && 0x08) > 0 // maybe =1 ?
		diff = -E 
		else
		diff = E
	endif	
	
    samp = coder_stat.last + diff // stat.last instead of coder_stat without global

    /*
    *  Clip the values to +(2^11)-1 to -2^11. (12 bits 2's
    *  compelement)
    *  Note: previous version errantly clipped at +2048, which could
    *  cause a 2's complement overflow and was likely the source of
    *  clipping problems in the previous version.  Thanks to Frank
    *  van Dijk for the correction.  TLB 3/30/04
    */
    if( samp > 2047 )
       samp = 2047
    endif
    if( samp < -2048 )
      samp = -2048
    endif

    coder_stat.last = samp // changed stat to coder_stat, because of *Pointer reference don't know how
    coder_stat.step_index = coder_stat.step_index  + step_adjust( code )
    if( coder_stat.step_index < 0 ) : coder_stat.step_index = 0 : endif
    if( coder_stat.step_index > 48 ) : coder_stat.step_index = 48 : endif
		
	// how does stat will be returned?	
	// because of that, or the variable would not be set directly, I decided to make coder_stat global

    
Endfunction samp

Function LoadSoundVOX(filename$,frequenz)
	
	Channels = 1
	Bits = 16
	// Mono, 16 Bit
		
	adpcm_init( coder_stat ) // it's global, don't know, how to make a reference pointer *coder_stat
	
  SoundID = -1

	adpcmem = CreateMemblockFromFile(filename$) // vox without header RAW 4 Bit
	// 1 Byte contains 2 Samples. "1 Byte contains 4 Bytes"
	
	mox = CreateMemblock(GetMemblockSize(adpcmem)*4+12) // +12 for Header
	
	SetMemblockByte(mox,0,Channels)  // mono
	SetMemblockByte(mox,2,Bits) // 16 Bit
	SetMemblockInt (mox,4,frequenz) // 44100
	SetMemblockInt (mox,8,GetMemblockSize(adpcmem)*2) // 4
	
	// buffer12 is mox
		
	for i=0 to GetMemblockSize(adpcmem)-1
	
	
	SetMemblockShort(mox,12+i*4+0,adpcm_decode( (GetMemblockByte(adpcmem,i)>>4)&&0x0f )*16)
    SetMemblockShort(mox,12+i*4+2,adpcm_decode( GetMemblockByte(adpcmem,i)&&0x0f )*16)			
    
	
	Next
	
		
	//--- create SoundHeader ---
		
	soundID = CreateSoundFromMemblock(mox)

    // was for test only, is not a real WAVE-RIFF File, but works in AudaCity as RAW
	CreateFileFromMemblock("_testfile_44100_16Bit_Mono.raw",mox)
	DeleteMemblock(mox)
	DeleteMemblock(adpcmem)
	
EndFunction soundID	

voxid = LoadSoundVOX("woman_16-bit_44KHz_master.vox",44100) // Mono Only supported, but could be changed easily 





If  voxid <> -1
  PlaySound(voxid)	
EndIf	



do  

    Print( "DeVOX, plays VOX-Files, ADPCM 4 Bit converts to 16 Bit FPS: "+Str(ScreenFPS(),2) )
    Print(voxid)
    Sync()
loop