Motorola DSP Developer's Kit

round-c.asm

[ X ] = mot###_dspround( X ) 

Description

This function rounds the elements of complex input vector X to the nearest integer

Input/Output

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

Output: Xr, Xi

Algorithm

for(i=0; i<size; i++)
{
    if (Xr[i] <= -0.5)
        Xr[i] = -1;
    else if(Xr[i] >= 0.5)
        Xr[i] = 1;
    else
        Xr[i] = 0;
    if (Xi[i] <= -0.5)
        Xi[i] = -1;
    else if(Xi[i] >= 0.5)
        Xi[i] = 1;
    else
        Xi[i] = 0;
}

Memory & Register:

Memory allocations:

X memory:

• Label IN_REAL stores the start address of the real input data
• Label OT_REAL stores the start address of the real result

Y memory

• Label IN_IMAG stores the start address of the imaginary input data
• Label OT_IMAG stores the start address of the imaginary result

Register usage:

• R7 stores the length of the input of the complex vector X

Status Register

The assembly function round-c.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.

round-r.asm

sort-r1.asm