ssGetDataTypeIsScalingPow2

Determine whether registered data type has power-of-two scaling

Syntax

extern int ssGetDataTypeIsScalingPow2 (SimStruct *S, DTypeId
                                       dataTypeId)

Arguments

S

SimStruct representing an S-function block.

dataTypeId

Data type ID of the registered data type for which you want to know whether the scaling is strictly power-of-two.

Description

This function determines whether the registered data type is scaled strictly by a power of two. Fixed-point numbers can be represented as

real-world value = (slope × integer) + bias,

where the slope can be expressed as

slope = fractional slope × 2^exponent.

When bias  = 0 and fractional slope  = 1, the only scaling factor that remains is a power of two:

real-world value = (2^exponent × integer) = (2^{-fraction length} × integer).

Trivial scaling is considered a case of power-of-two scaling, with the exponent being equal to zero.

Note

Many fixed-point algorithms are designed to accept only power-of-two scaling. For these algorithms, you can call ssGetDataTypeIsScalingPow2 in mdlSetInputPortDataType and mdlSetOutputPortDataType, to prevent unsupported data types from being accepted.

This function errors out when ssGetDataTypeIsFxpFltApiCompat returns FALSE.

Requirements

• To use this function, you must include fixedpoint.h and fixedpoint.c. For more information, see Structure of the S-Function.

• To build an S-function that utilizes this function, you must compile it using the mex function with -lfixedpoint argument. For more information, see Create MEX Files.

Languages

C

TLC Functions

FixPt_DataTypeIsScalingPow2