Motorola DSP Developer's Kit

abs-c.asm

Motorola DSP Developer's Kit

abs-c.asm

Motorola DSP Developer's Kit

abs-c.asm

Y = mot###_abs( X )

Input/Output

Input: Complex vector X (includes real part Xr, and imaginary part Xi)

Output: Real vector Y

Algorithm

for ( i=0; i <size( X ); i++ )
{
Intervalue = Xr[i] * Xr[i];
Intervalue += Xi[i] * Xi[i];
y[i] = sqrt-sr(Intervalue >> 1);
}

Note    If absolute values are desired, the scaling up factor is sqrt(2). For a description of function sqrt-sr, refer to sqrt-sr.asm.

Memory & Register

Memory allocation and register usage:

• Start address of the real part of vector X is defined in label IN_REAL
• Start address of the imaginary part of vector X is defined in label IN_IMAG
• Size of vector X is stored in register R7
• Start address of output vector Y is defined in label OUT

Status Register

The assembly function abs-c.asm does not explicitly set any status register bits during the function execution.

Data Size Limit

The length of vector X is limited by the size of available continuous data memory.

Data Range Limit

The input vector X range is [-1.0, +1.0].

Precision

In the case of DSP563, precision is 23 bits.

In the case of DSP566, precision is 15 bits.

Performance Limit

In the case of DSP563, there are 222 cycles for each element of input data.

In the case of DSP566, there are 150 cycles for each element of input data.

abs-r.asm

angle-c.asm