function?raw_y?=?adpcm_decoder（adpcm_y）?
?
%?This?m-file?is?based?on?the?app?note:?AN643?Adaptive?differential?pulse?
%?code?modulation?using?PICmicro?microcontrollers?Microchip?Technology?
%?Inc.?The?app?note?is?avaialbe?from?www.microchip.com?
%?Example:??Y?=?wavread（‘test.wav‘）;?
%???????????y?=?adpcm_encoder（Y）;?
%???????????YY?=?adpcm_decode（y）;?
IndexTable?=?[-1?-1?-1?-1?2?4?6?8?-1?-1?-1?-1?2?4?6?8];?
??????????
StepSizeTable?=?[7?8?9?10?11?12?13?14?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?1707?1878?2066?2272?2499?2749?3024?3327?3660?4026?4428?4871?5358?5894?6484?7132?7845?8630?9493?10442?11487?12635?13899?15289?16818?18500?20350?22385?24623?27086?29794?32767];?
?
prevsample?=?0;?
previndex?=?1;?
?
Ns?=?length（adpcm_y）;?
n?=?1;?
?
while?（n?<=?Ns）?
????predsample?=?prevsample;?
????index?=?previndex;?
????step?=?StepSizeTable（index）;?
????code?=?adpcm_y（n）;?
?
????diffq?=?bitshift（step?-3）;?
????if?（bitand（code?4））?
????????diffq?=?diffq?+?step;?
????end?
????if?（bitand（code?2））?
????????diffq?=?diffq?+?bitshift（step?-1）;?
????end?
????if?（bitand（code?1））?
????????diffq?=?diffq?+?bitshift（step?-2）;?
????end?
?
????if?（bitand（code?8））?
????????predsample?=?predsample?-?diffq;?
????else?
????????predsample?=?predsample?+?diffq;?
????end?
?
????if?（predsample?>?32767）?
????????predsample?=?32767;?
????elseif?（predsample?????????predsample?=?-32768;?
????end?
?
????index?=?index?+?IndexTable（code+1）;?
?
????if?（index?????????index?=?1;?
????end?
????if?（index?>?89）?
????????index?=?89;?
????end?
?
????prevsample?=?predsample;?
????previndex?=?index;?
?
????raw_y（n）?=?predsample?/?32767;?
????n?=?n?+?1;?
end

?屬性????????????大小?????日期????時間???名稱
-----------?---------??----------?-----??----

?????文件?????285178??2009-09-03?22:05??work\2.wav

?????文件???????7390??2009-09-03?21:43??work\3.wav

?????文件??????54324??2009-09-03?21:51??work\4.wav

?????文件??????69278??2009-09-03?22:42??work\5.wav

?????文件???????1981??2009-09-14?20:19??work\adpacm\adpcm_decoder.m

?????文件???????2573??2009-09-14?20:19??work\adpacm\adpcm_encoder.m

?????文件????????288??2009-09-13?12:24??work\char\char_s.asv

?????文件????????288??2009-09-13?12:24??work\char\char_s.m

?????文件???????1019??2009-09-13?18:52??work\huffman\huffman.asv

?????文件???????1025??2009-09-13?19:10??work\huffman\huffman.m

?????文件??????40703??2009-09-14?10:30??work\music\1.txt

?????文件??????28022??2009-09-14?10:37??work\music\2.txt

?????文件??????28022??2009-09-14?10:38??work\music\3.txt

?????文件??????40703??2009-09-14?10:46??work\music\4.txt

?????文件??????24023??2009-09-14?11:21??work\music\5.txt

?????文件??????24023??2009-09-14?11:22??work\music\6.txt

?????文件??????22682??2009-09-14?11:27??work\music\7.txt

?????文件??????17783??2009-09-14?12:04??work\music\8.txt

?????文件??????31094??2009-09-14?11:19??work\music\新建?文本文檔?（2）.txt

?????文件??????40703??2009-09-14?09:10??work\music\白噪聲.txt

?????文件????????929??2009-09-12?11:22??work\pcm\pcm.m

?????文件????????999??2009-09-12?10:33??work\pcm\pcm_decode.asv

?????文件????????982??2009-09-12?10:34??work\pcm\pcm_decode.m

?????文件????????771??2009-09-12?10:38??work\pcm\pcm_decode_test.asv

?????文件????????760??2009-09-12?13:24??work\pcm\pcm_decode_test.m

?????文件????????921??2009-09-12?09:28??work\pcm\pcm_test.asv

?????文件????????527??2009-09-12?14:26??work\pcm\pcm_test.m

?????文件???????1004??2009-09-14?19:17??work\pcm\pcm_xcor.asv

?????文件???????1003??2009-09-14?19:17??work\pcm\pcm_xcor.m

?????文件?????509742??2009-09-03?17:43??work\test1.wav

............此處省略33個文件信息