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Keil C166 Compiler

Preprocessor Symbols

Sets preprocessor symbols which may be checked with #if, #ifdef and #ifndef. The defined names are copied exactly as they are entered (case-sensitive). Each name may get optionally a value. Define: Check, NoExtRam, X1=1+5 is identical to the following C preprocessor #define statements:
   #define Check
   #define NoExtRam
   #define X1 1+5
Clears previous Define assignments that are entered in the options dialog of a higher Target or Group level.

Code Optimization

Set the optimization level the Compiler uses when generating object code.
Specify whether the Compiler should optimize for code size or execution speed.
Global Register Coloring
Enable application wide register optimization. When set the C166 compiler knows the registers used by external functions and µVision performs automatically iterative re-translations of C source files to improve the register allocation.
Reorder Instructions to Minimize Pipeline Effects
Reorder instructions to minimize wait states and pipeline stalls for the XE16x and XC20x device variants.
Use Static Memory for Non-Register Automatics
When enabled, the Compiler uses static memory locations for automatic variables (not parameters) that cannot be allocated to a CPU register. The generated code is not reentrant but code size is reduced and execution speed is improved.
Alias Checking on Pointer Accesses
When disabled, the Compiler ignores pointer write operations during the optimization phase. If a register holds a variable, the variable is reused, even when access through a pointer might have modified that variable. Disable this option to reduce program size when you are confident that your program does not modify variables through pointers.

Other Controls

Allows you to suppress compiler warnings.
Keep Variables in Order
Order all variables in memory according to their order of definition in the C source file.
Treat 'char' as 'unsigned char'
Instructs the Compiler to treat all variables declared with plain char as unsigned char variables.
Save DPP on Interrupt Entry
This option improves the performance of interrupt functions and instructs the compiler not to preserve the DPP0 and DPP3 registers inside interrupt functions. Enable this option when you are certain that DPP0 and DPP3 registers are not altered in assembly subroutines which are called by interrupt functions. 
Double-precision Floating Point
Enable 64-bit (double-precision) floating-point math when the double type is used in your C programs. The float type continues to use 32-bit floating-point math. When disabled, all floating-point math is performed using 32-bits (even when the double type is specified).
Save Temporary Variables on User Stack
Instructs the Compiler to save temporary results and saved-by-callee variables on the user stack. This option may be necessary if you run out of system stack space.
Include Paths
Allows you to supply one or more (separated by semi-colon) paths to search for header files. For
#include "filename.h"
the Compiler searches first the current folder and then folder of the source file. When this fails or when
#include <filename.h>
is used, the paths specified in the include paths box are searched. When this still fails, the paths specified in for the INC folder under Project - Manage - Project Items are used.
Misc Controls
Specify any assembler directive for which there is no individual dialog control.
Compiler Control String
Displays the current directives at the Compiler command line.
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