Hi Tony,
first I wanted to write you this:
"
if I would have to deal with a structure complicated as yours is, I wouldn't hesitate to update the whole structure at once. You could rearrange you ChannelAtt-struct to have everything more processor (alingment) friendly. Try to order the members by data-size. Move 4-byte values to the top and 1-byte values (like Boolean) to the bottom.
"
But at another lokk at your struct I saw the Char* Filename. This will not go into a record without converting. So should maybe rearrange the struct like:
typedef struct{
ChannelAtt CH[6];
StereoModeType StereoMode;
Char FileName[0];
} OemiDBRecordType;to save it into the record. You would have to allocate sizeof(OemiDBRecordType) + StrLen(FileName) + 1; bytes
Then you first dump the record and later on the FileName + 0-byte.
just my 2 cents Henk
Tony Janke wrote:
I am trying to store a data structure in a record and have a few questions. There seems to be (at least) 2 ways to store data in a record. You can either create a new record, and over write an old record with the new copy that contains the new field values. The other way is to edit the individual fields that were changed. I'd think it would be much more efficient to modify only the necessary fields and that brings me to my first question.
The example documentation uses a simple struct:
typedef struct { char FirstName[20]; char LastName[20]; char PhoneNum[20]; } DBRecord; typedef DBRecord DBRecordType; typedef DBRecord* DBRecordPtr;
then when a field (say Last Name) is changed, a simple:
(MemHandle) h = DmGetRecord(gDatabase, index); if (h) { // could fail due to out of memory! DBRecordType * p = (DBRecordType *) MemHandleLock(h); // write only the changed fields of record instead of the whole record Err err = DmWrite(p, OffsetOf(DBRecordType, LastName), "Knopp", 20); MemPtrUnlock(p); DmReleaseRecord(gDatabase, index, true);
will replace the old last name with the new one.
My structure is as follows:
typedef struct{ UInt8 _30Hz; UInt8 _60Hz; UInt8 _120Hz; UInt8 _250Hz; UInt8 _500Hz; UInt8 _1000Hz; UInt8 _2000Hz; UInt8 _4000Hz; UInt8 _8000Hz; UInt8 _16000Hz; } EQFreq;
typedef UInt8 FilterType; enum FilterType{HighPass, LowPass, ByPass}; typedef UInt8 MixerType; enum MixerType{NONE, A, AB, AC, ABC, B, BC, C}; typedef UInt8 StereoModeType; enum StereoModeType{LEFT, RIGHT, STEREO}; typedef Char* FileName; typedef struct{ Boolean STEREO; // Stereo Linked? EQFreq EQ; // 10-band EQ settings MixerType MIXER; // Mixer controls FilterType FILTER; // Filter type (HP/LP/BP) UInt8 VOLUMELEVEL; // Volume Level UInt16 FILTERFREQ; // Filter Fc UInt8 DELAY; // Delay in 100's of uS Boolean MUTE; // Is Muted? T/F Boolean SOLO; // Is SOLO? T/F } ChannelAtt; typedef struct{ Char* FileName; ChannelAtt CH[6]; // Channel 0 used for Tune Mode StereoModeType StereoMode; // Channel mode, Left, Right or Stereo Link } OemiDBRecordType;
To modify the 30Hz filter value for say channel 4, I would normally do a:
OemiDBRecordType Vehicle;
UInt8 newFreq = 50; Vehicle.CH[4].EQ._30Hz = newFreq;
Currently, I have a global variable (Vehicle) that I can access in any function, but I wanna change that and store the data in records. How would I change that value using the DmWrite function? my goal is to use each record as a "file" so that the user can select between different setups by choosing different records.
Also, while trying to troubleshoot my code, I am using the simulator to look at my Database and record data. I can see the database and the records I create, but I don't know how to decipher the data I see in that record. When I assign a value to a variable and write that value to the record, I see that some of the record values change but don't know how to interpret those changes to verify they are correct. How do read these values and is there a way to see a database and record during debugging?
thanks in advance!
~Tony
-- ------------------------------------------------------------------------- Henk Jonas Palm OS ® certified developer
[EMAIL PROTECTED] www.metaviewsoft.de -------------------------------------------------------------------------
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