ADDRESSING
MOTOROLA
ADDRESS GENERATION UNIT
4 - 25
4.4.2.4
Address-Modifier-Type Encoding Summary
There are three address modifier types:
•
Linear Addressing
•
Reverse-Carry Addressing
•
Modulo Addressing
Bit-reverse addressing is useful for 2
k
-point FFT addressing. Modulo addressing is useful
for creating circular buffers for FIFOs (queues), delay lines, and sample buffers up to
32,768 words long. The linear addressing is useful for general-purpose addressing. There
is a reserved set of modifier values (from 32,768 to 65,534) that should not be used.
Figure 4-15 gives examples of the three addressing modifiers using 8-bit registers for sim-
plification (all AGU registers are 16 bit). The addressing mode used in the example,
postincrement by offset Nn, adds the contents of the offset register to the contents of the
address register after the address register is accessed. The results of the three examples
are as follows:
•
The linear address modifier addresses every fifth location since the offset register
contains $5.
•
Using the bit-reverse address modifier causes the postincrement by offset Nn
addressing mode to use the address register, bit reverse the four LSBs, increment by
1, and bit reverse the four LSBs again.
•
The modulo address modifier has a lower boundary at a predetermined location, and
the modulo number plus the lower boundary establishes the upper boundary. This
boundary creates a circular buffer so that, if the address register is pointing within the
boundaries, addressing past a boundary causes a circular wraparound to the other
boundary.
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 ...