| Fixed-Point Blockset | |
Parameters of fixed-point blocks that accept numerical values are always converted from a double to a Fixed-Point Blockset data type. Parameters can be converted to the input data type, the output data type, or to a data type explicitly specified by the block. For example, the FIR block converts the Initial condition parameter to the input data type, and converts the FIR coefficients parameter to a data type you explicitly specify via the block dialog box.
Parameters are always converted before any arithmetic operations are performed. Additionally, parameters are always converted offline using round-to-nearest and saturation. Offline conversions are discussed below.
For information about parameter conversions for a specific block, refer to Block Reference.
Offline Conversions
An offline conversion is a conversion performed by your development platform (for example, the processor on your PC), and not by the fixed-point processor you are targeting. For example, suppose you are using a PC to develop a program to run on a fixed-point processor, and you need the fixed-point processor to compute
over and over again. If a, b, and c are constant parameters, it is inefficient for the fixed-point processor to compute ab/c every time. Instead, the PC's processor should compute ab/c offline one time, and the fixed-point processor computes only 
. This eliminates two costly fixed-point arithmetic operations.
| | Parameter and Signal Conversions | Signal Conversions | |