-- Adaptive Delta PCM

-- really Adaptive predictive PCM since we are not using 1.0 as

-- predictor coefficient

-- L. Stewart, last updated: August 28, 1979 3:12 PM

AdpcmDefs: DEFINITIONS =

BEGIN

PcmHandle: TYPE = DESCRIPTOR FOR PACKED ARRAY OF [0..377B];

AdpcmHandle: TYPE = DESCRIPTOR FOR ARRAY OF CARDINAL;

AdpcmState: TYPE = RECORD

[

pred: INTEGER,

mode: CARDINAL,

now: CARDINAL,

hist: INTEGER,

PVal: CARDINAL

];

InitAdpcm: PROCEDURE;

InitAdpcmState: PROCEDURE [statep: POINTER TO AdpcmState];

CompressBlock: PROCEDURE [pcmData: PcmHandle, cData: AdpcmHandle, count: INTEGER, initialState: AdpcmState] RETURNS [AdpcmState];

DeCompressBlock: PROCEDURE [pcmData: PcmHandle, cData: AdpcmHandle, count: INTEGER, initialState: AdpcmState] RETURNS [AdpcmState];

END.