6.5.  TN_DUR: Tone Duration

The TN_DUR structure is declared as follows:

typedef  struct {

   short int tn_on;            /* Cadence on-time (10msec)    */

   short int tn_ondev;         /* on-time deviation (10msec)  */

   short int tn_off;           /* Cadence off-time (10msec)   */

   short int tn_offdev;        /* off-time deviation (10msec) */

} TN_DUR;

The TN_DUR structure specifies cadence information for a tone and is a member of the TN_DESC structure.

The TN_DESC structure is used in two different parameters of the lm_LearnTone( ) function, and serves the following purposes:

• tn_rangep (input): Specifies optional tone learning boundaries as input to the lm_LearnTone( ) function, restricting learning to the specified range.
• tn_tonep (input): Specifies an existing tone description as optional input to the lm_LearnTone( ) function, and which learn mode incorporates in the final tone description.
• tn_tonep (output): Provides the final tone description that is returned by lm_LearnTone( ).

Use the lm_clrdesc( ) function to clear the fields of a TN_DESC structure, including the fields in the TN_FREQ and TN_DUR structures.

Table 4.  TN_DUR Structure

Field	Description
tn_on	Length: 2 (short int) Units: 10 ms Range: 0 -- 1000 Tone-On Time. Specifies the tone-on duration in 10 ms units for the tone cadence.
tn_ondev	Length: 2 (short int) Units: 10 ms Range: -1000 -- 1000 Tone-On Time Deviation. Specifies the deviation of the tone-on duration in 10 ms units for the tone cadence. This deviation is subtracted from and added to tn_on to define the minimum and maximum on-time for the cadence.
tn_off	Length: 2 (short int) Units: 10 ms Range: 0 -- 1000 Tone-Off Time. Specifies the tone-off duration in 10 ms units for the tone cadence.
tn_offdev	Length: 2 (short int) Units: 10 ms Range: -1000 -- 1000 Tone-Off Time Deviation. Specifies the deviation of the tone-off duration in 10 ms units for the tone cadence. This deviation is subtracted from and added to tn_off to define the minimum and maximum off-time for the cadence.

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