Motorola DSP Developer's Kit

diff-r.asm

Motorola DSP Developer's Kit

diff-r.asm

B = mot###_diff(A,N)

This function performs an N-th order difference between the elements of real vector A.

INput/Output

Input: Real vector A, int N (N-th order)

Output: Real vector B

Algorithm

for ( i = 1; i <= N; i ++ ) {
    for ( j = 1; j <= LengthA - 1; j ++ ) {
        A[j] = A[j + 1] - A[j];
   }
   -- LengthA;
}
B = A;

Memory & Register

Memory allocation and register usage:

• R2 stores the length of A
• R3 stores the input N
• R4 stores the start address of vector A
• R0 stores the index of vector A
• R1 stores the index of vector B
• R2 and R3 are used as loop control

Assume M{0...7} = $ffff

Status Register

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

Data Size Limit

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

Data Range Limit

The value of input vector 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.

Performance Limit

DSP563:

DSP566:

decimate-iir-c.asm

diff-c.asm