Texas Instruments TI-89 - Getvalue

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Appendix A: System Routines — EStack Utilities
TI
-
89 / TI
-
92 Plus Developer Guide
Not for Distribution
Beta Version January 26, 2001
GetValue
Declaration:
long
GetValue
(EStackIndex
indx
, long
rLow
, long
rHigh
)
Category(ies):
EStack Utilities, EStack Arithmetic
Description:
Get a value from the estack in the range
rLow
to
rHigh
. Throw an
ER_DOMAIN error if not in range. Throw an ER_DATATYPE error if the
estack does not contain an integer or a number that can be converted to an
integer.
Inputs:
indx
— Indexes the location of the estack to retrieve the value from.
rLow
— The low range of accepted values.
rHigh
— The high range of accepted values.
Outputs:
Value in the range
rLow
to
rHigh
.
Assumptions:
None
Side Effects:
May throw an ER_DOMAIN or ER_DATATYPE error.
Availability:
On AMS 1.05 and higher.
TI-89 / TI-92 Plus
Differences:
None
See Also: estack_to_short, estack_to_ushort
Example:
This example is used by the graphing commands in TI
-
BASIC to get the
user supplied screen attribute value. It returns the attribute value after
mapping it from a user supplied integer in the range -1 to +1.
/* Get a valid attribute value (0,1,-1) and return its corresponding
screen attribute (A_REVERSE, A_NORMAL, A_XOR).
*/
short GetAttr( EStackIndex i )
{ Access_AMS_Global_Variables;
SWORD RetInt;
RetInt = GetValue( i, -1, 1 );
if (RetInt == -1)
return A_XOR;
else if (RetInt == 0)
return A_REVERSE;
else
return A_NORMAL;
}