SAF-C164SM Infineon Technologies, SAF-C164SM Datasheet - Page 23

• Manufacturer Part Number: SAF-C164SM
• Description: 16-Bit CMOS Microcontroller
• Manufacturer: Infineon Technologies

High Performance Branch-, Call-, and Loop Processing
Due to the high percentage of branching in controller applications, branch instructions
have been optimized to require one extra machine cycle only when a branch is taken.
This is implemented by precalculating the target address while decoding the instruction.
To decrease loop execution overhead, three enhancements have been provided:
• Single cycle branch execution after the first iteration of a loop:
• Detection of the end of a table:
• Compare and Increment or Decrement instructions:
The system state information is saved automatically on the internal system stack, thus
avoiding the use of instructions to preserve state upon entry and exit of interrupt or trap
routines. Call instructions push the value of the IP on the system stack, and require the
same execution time as branch instructions. Additionally, instructions have been
provided to support indirect branch and call instructions. This feature supports
implementation of multiple CASE statement branching in assembler macros and high
level languages.
User’s Manual
The first solution provides that only one machine cycle is lost during the execution of
the entire loop. In loops which fall through upon completion, no machine cycles are
lost when exiting the loop. No special instructions are required to perform loops, and
loops are automatically detected during execution of branch instructions.
The second loop enhancement avoids the use of two compare instructions embedded
in loops. One simply places the lowest negative number at the end of the specific table
and specifies branching if neither its value nor the compared value have been found.
Otherwise, the loop is terminated if either condition has been met. The terminating
condition can then be tested.
The third loop enhancement provides a more flexible solution than the Decrement and
Skip on Zero instruction found in other microcontrollers. The use of Compare and
Increment or Decrement instructions enables the user to make comparisons to any
value. This allows loop counters to cover any range and is particularly advantageous
in table searching.
2-6
Architectural Overview
C164CM/C164SM
Derivatives
V1.0, 2002-02