ADDRESSING
MOTOROLA
ADDRESS GENERATION UNIT
4 - 19
(base address), it will wrap around through the base address plus M–1 (upper boundary).
If an offset (Nn) is used in the address calculations, the 16-bit absolute value, |Nn|, must
be less than or equal to M for proper modulo addressing in this range. If Nn>M, the result
is data dependent and unpredictable, except for the special case where Nn=P x 2
k
, a mul-
tiple of the block size where P is a positive integer. For this special case, when using the
(Rn)+ Nn addressing mode, the pointer, Rn, will jump linearly to the same relative address
in a new buffer, which is P blocks forward in memory (see Figure 4-12).
Similarly, for (Rn)–Nn, the pointer will jump P blocks backward in memory. This technique
is useful in sequentially processing multiple tables or N-dimensional arrays. The range of
values for Nn is –32,768 to + 32,767. The modulo arithmetic unit will automatically wrap
around the address pointer by the required amount. This type of address modification is
useful for creating circular buffers for FIFOs (queues), delay lines, and sample buffers up
to 32,768 words long as well as for decimation, interpolation, and waveform generation.
The special case of (Rn)
±
Nn mod M with Nn=P x 2
k
is useful for performing the same
algorithm on multiple blocks of data in memory — e.g., parallel infinite impulse response
(IIR) filtering.
An example of address register indirect modulo addressing is shown in Figure 4-13. Start-
ing at location 64, a circular buffer of 21 stages is created. The addresses generated are
offset by 15 locations. The lower boundary = L x (2
k
) where 2
k
≥
21; therefore, k=5 and
the lower address boundary must be a multiple of 32. The lower boundary may be chosen
CIRCULAR
BUFFER
ADDRESS
POINTER
M = MODULUS
UPPER BOUNDARY
LOWER BOUNDARY
Figure 4-11 Circular Buffer
Summary of Contents for DSP56K
Page 12: ...xii LIST of TABLES MOTOROLA List of Tables Continued Table Page Number Title Number ...
Page 13: ...MOTOROLA DSP56K FAMILY INTRODUCTION 1 1 SECTION 1 DSP56K FAMILY INTRODUCTION ...
Page 31: ...MOTOROLA DATA ARITHMETIC LOGIC UNIT 3 1 SECTION 3 DATA ARITHMETIC LOGIC UNIT ...
Page 50: ...DATA ALU SUMMARY 3 20 DATA ARITHMETIC LOGIC UNIT MOTOROLA ...
Page 51: ...MOTOROLA ADDRESS GENERATION UNIT 4 1 SECTION 4 ADDRESS GENERATION UNIT ...
Page 77: ...MOTOROLA PROGRAM CONTROL UNIT 5 1 SECTION 5 PROGRAM CONTROL UNIT ...
Page 124: ...INSTRUCTION GROUPS 6 30 INSTRUCTION SET INTRODUCTION MOTOROLA ...
Page 125: ...MOTOROLA PROCESSING STATES 7 1 SECTION 7 PROCESSING STATES STOP WAIT EXCEPTION NORMAL RESET ...
Page 167: ...STOP PROCESSING STATE MOTOROLA PROCESSING STATES 7 43 ...
Page 168: ...STOP PROCESSING STATE 7 44 PROCESSING STATES MOTOROLA ...
Page 169: ...MOTOROLA PORT A 8 1 SECTION 8 PORT A ...
Page 176: ...PORT A INTERFACE 8 8 PORT A MOTOROLA ...
Page 177: ...MOTOROLA PLL CLOCK OSCILLATOR 9 1 SECTION 9 PLL CLOCK OSCILLATOR x x d Φ VCO ...
Page 191: ...10 2 ON CHIP EMULATION OnCE MOTOROLA SECTION 10 ON CHIP EMULATION OnCE ...
Page 218: ...USING THE OnCE MOTOROLA ON CHIP EMULATION OnCE 10 29 ...
Page 604: ...INSTRUCTION ENCODING A 338 INSTRUCTION SET DETAILS MOTOROLA ...
Page 605: ...MOTOROLA BENCHMARK PROGRAMS B 1 APPENDIX B BENCHMARK PROGRAMS T T T T T P1 P3 P2 P4 T T T ...
Page 609: ...BENCHMARK PROGRAMS MOTOROLA BENCHMARK PROGRAMS B 5 ...
Page 611: ...BENCHMARK PROGRAMS MOTOROLA BENCHMARK PROGRAMS B 7 ...
Page 613: ...BENCHMARK PROGRAMS MOTOROLA BENCHMARK PROGRAMS B 9 ...
Page 615: ...BENCHMARK PROGRAMS MOTOROLA BENCHMARK PROGRAMS B 11 ...