PROGRAMMING MODEL
5 - 14
PROGRAM CONTROL UNIT
MOTOROLA
tions. The DSP56K software simulator accurately shows how the MPY, MAC, and other
Data ALU instructions operate while the processor is in the double precision multiply
mode.
5.4.2.14
Loop Flag (Bit 15)
The loop flag (LF) bit is set when a program loop is in progress. It detects the end of a
program loop. The LF is the only SR bit that is restored when a program loop is termi-
nated. Stacking and restoring the LF when initiating and exiting a program loop, respec-
tively, allow the nesting of program loops. At the start of a long interrupt service routine,
the SR (including the LF) is pushed on the SS and the SR LF is cleared. When returning
from the long interrupt with an RTI instruction, the SS is pulled and the LF is restored.
During a processor reset, the LF is cleared.
5.4.3 Operating Mode Register
The OMR is a 24-bit register (only six bits are defined) that sets the current operating
mode of the processor. Each chip in the DSP56K family of processors has its own set of
operating modes which determine the memory maps for program and data memories, and
the startup procedure that occurs when the chip leaves the reset state. The OMR bits are
only affected by processor reset and by the ANDI, ORI, and MOVEC instructions, which
directly reference the OMR.
The OMR format with all of its defined bits is shown in Figure 5-6. For product-specific
OMR bit definitions, see the individual chip’s user manual for details on its respective op-
erating modes.
5.4.4 System Stack
The SS is a separate 15X32-bit internal memory divided into two banks, the SSH and the
*
SD
MC YD
DE MB MA
23
8
7
6
5
4
3
2
1
0
*
OPERATING MODE A, B
DATA ROM ENABLE
INTERNAL Y MEMORY DISABLE
OPERATING MODE C
RESERVED
STOP DELAY
RESERVED
RESERVED
*
Figure 5-6 OMR Format
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 ...
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