Keyboard Shortcuts
Likes
Search
Xpander sysex patch spec- the Xplorer version
|
I'm trying to understand the calculations that the single patch browser (included with Xplorer) ueses. Looking at XpanderSysEx.h // Single patch data sysex length is 399 bytes // 6 bytes for sysex intro: F0 10 02.... static const int PRG_DUMP_DATA_FOLLOWS_INTRO_LENGTH = 6; // 188 double bytes data for the values and 8 double bytes for the patch name static const int PATCHNAME_LENGTH = 8; static const int OBWORDS_DATA_LENGTH = 196 - PATCHNAME_LENGTH; // 6 (intro) +196*2 (data+name) +1 (EOX) = 399 I understand that?PRG_DUMP_DATA_FOLLOWS_INTRO_LENGTH is for the Sysex cmd overhead to request a single patch, however, I don't understand why he subtracts the patchname length from 196, when the patch name is part of each single patch. 196 & 2 + 8 = 399 bytes, which is correct What am I missing? |
|
I think the comments explain it: "188 double bytes data for the values and 8 double bytes for the patch name" What is meant by "double bytes" is some form of encoding bytes (8-bit values) into sysex data, which is a string of 7-bit values. Often this means splitting a byte into a high nibble and a low nibble (4+4 bits) but I don't know if that's what the Xpander does. Also see the second comment: "6 (intro) +196*2 (data+name) +1 (EOX) = 399" So 7 MIDI bytes of framing, leaving 399-7=392 sysex data "bytes" (7-bit values). Divide that by 2, and you get 196 proper bytes (8-bit values).
|
|
>>?196 & 2 + 8 = 399 bytes, which is correct I have to correct my own calculation, however it still doesn't add up from what i can see. 196 *2 = 392 bytes, including the patch name. Add the first 6 bytes for the sysex command, + 1 EOX, 399 bytes. On Tue, May 22, 2018 at 1:46 PM, cappy2112@... [xpantastic] <xpantastic@...> wrote:
|
|
Hi, you should look at the XpanderSinglePatchViewer.cpp, it is self explanatory there. you have OBWORDS_DATA_LENGTH of data to be "repacked" as double byte values, which is not required of course for the patch name (string) that comes afterward. ??? // for each double byte, repack the value, and set the Patch property accordingly ??? unsigned char* pByte= (unsigned char*)pPatch; ??? for (int i=0;i<OBWORDS_DATA_LENGTH;i++) { ??? ??? // 8th bit of the 8 bits value is the first bit of the high byte ??? ??? unsigned char cValue = ((shortArray[i] & 0x0100)>>1) | (shortArray[i] & 0x00ff); ??? ??? *pByte=cValue; ??? ??? pByte++; ??? } ... ??? // name is 2 bytes/char, high byte never used, thus wchar_t compatible ??? iReadBytes=0; ??? iReadBytes=fread(&pPatch->name,sizeof(wchar_t),PATCHNAME_LENGTH,pFile); ??? assert(iReadBytes==PATCHNAME_LENGTH); Regards, |