PM0014 datasheet(18/46 Pages) STMICROELECTRONICS

Teilenummer	PM0014

Bauteilbeschribung	General-purpose DSP library

PDF	46 Pages

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Hersteller	STMICROELECTRONICS [STMicroelectronics]

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Arithmetic library functions

PM0014

18/46

5.3.2

sub_32

sub_32 (short LeftOpMsb, short LeftOpLsb, short RightOpMsb,

short RightOpLsb, long *Output)

Description:

Subtraction of two real 32-bit inputs.

Argument:

LeftOpMsb

Left operand most significant bits.

LeftOpLsb

Left operand least significant bits.

RightOpMsb

Right operand most significant bits.

RightOpLsb

Right operand least significant bits.

Output

Output pointer.

Algorithm:

LeftOp - RightOp = Output

Note:

Set the MS bit-field of the MCW register to have a saturated result

(signed arithmetic).

Assembly source

code:

sub_32.asm

Code size and cycles: Size: 20 bytes

Instruction cycles: 14

Test:

Two files are provided to test the function: an input vector file

(Sub_32.in) and an output vector file (Sub_32.res):

Sub_32.in is made as follows:

LeftOpMsb1, LeftOpLsb1, RightOpMsb1, RightOpLsb1

...

Sub_32.res is made as follows:

OutputMsb1, OutputLsb1,...

PM0014 Datenblatt(PDF) 18 Page - STMicroelectronics