PM0014 datasheet(27/46 Pages) STMICROELECTRONICS

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PM0014

Arithmetic library functions

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5.5.3

cDiv_q31_q15_q15

cDiv_q31_q15_q15 (short LeftOpIMsb, short LeftOpILsb, short LeftOpRMsb,

short LeftOpRLsb, short RightOpI, short RightOpR, short *Output).

Description:

Division of two complex fractional inputs. Dividend is on 64 bits (32

bits for each part), divisor and quotient on 32 bits (16 bits for each

part).

Argument:

LeftOpIMsb

Left operand imaginary part most significant bits.

LeftOpILsb

Left operand imaginary part least significant bits.

LeftOpRMsb

Left operand real part most significant bits.

LeftOpRLsb

Left operand real part least significant bits.

RightOpI

Right operand imaginary part.

RightOpR

Right operand real part.

Output

Output pointer.

Algorithm:

Note:

Output imaginary part is contained in the lowest address (pointed

by Output). Output real part is in the highest address (pointed by

Output + 2).

If c2 + d2 is equal to 0, there is a result saturation to the maximum

positive value.

c2 + d2 must be smaller than the dividend real part and than the

dividend imaginary part for a valid result. Else, there is a result

saturation to the maximum positive or negative value.

If c2 + d2, ac + bd or bc - ad is greater than 1 or smaller than -1, it

saturates to the maximum positive or negative value.

If c2 + d2 and ac + bd or bc - ad are both a maximum value. The

real part of the result is not valid (respectively the imaginary part of

the result).

The implemented algorithm does not allow integer division. For

dividing integers (dividend in 32.0 format and divisor in 16.0), shift

the dividend one bit to the left (into 31.1 format) before dividing.

Assembly source

code:

cDiv_q31_q15_q15.asm

Code size and cycles: Size: 262 bytes

Instruction cycles: 470

aib

cid

--------------

--------------------i

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