Motorola DSP Developer's Kit

sqrt-pr.asm

Y = mot###_sqrt(X)

Description

This function returns square root of the elements of input vector X

Input/Output

Input: Vector X (elements of vector X are positive)

Output: Vector Y

Algorithm

Full 23(15) bit precision square root routine using a successive approximation technique.

for (i=0; i<size; i++)
{
Y[i] = Sqrt_sr (X[i]);
}

Memory & Register

Register usage:

• b is used for the output root
• a is used for temporary storage
• x0 is used for guess
• x1 is used for the bit being tested
• y0 is used for the input number
• r6 is used as the loop number (23 for 56300, 15 for 56600)

Status Register

The assembly function sqrt-pr.asm does not explicitly set any status registers/bits during the function execution.

Data Size Limit

The length of vector X can't be larger than the continuous available data memory size.

Data Range Limit

The value of input vector X must be between -1.0 and +1.0.

Precision

In the case of DSP563, precision is 23 bits.

In the case of DSP566, precision is 15 bits.

sqrt-sr.asm

sqrt-c.asm