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
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