TASKING VX-toolset for 8051 User Guide

TASKING VX-toolset for 8051 User GuideThe compiler always inlines the corresponding assembly instructions in the assembly source (rather thancalling it as a function).This avoids parameter passing and register saving instructions which are normallynecessary during function calls.Intrinsic functions produce very efficient assembly code. Though it is possible to inline assembly code byhand, intrinsic functions use registers even more efficiently. At the same time your C source remains veryreadable.You can use intrinsic functions in C as if they were ordinary C (library) functions. All intrinsics begin witha double underscore character (__).The TASKING VX-toolset for 8051 C compiler recognizes the following intrinsic functions:__allocvoid * volatile __alloc( __size_t size );Allocate memory. Returns a pointer to space in external memory of size bytes length. NULL if there isnot enough space left. This function is used internally for variable length arrays, it is not to be used byend users.__dotdotdot__char * volatile __dotdotdot__( void );Variable argument '...' operator. Used in library function va_start(). Returns the stack offset to thevariable argument list.__freevoid volatile __free( void *p );Deallocates the memory pointed to by p. p must point to memory earlier allocated by a call to __alloc().__getbit__bit __getbit( operand, bitoffset );Returns the bit at bitoffset (range 0-7 for a char, 0-15 for an int or 0-31 for a long) of the bit-addressableoperand for usage in bit expressions. bitoffset must be an integral constant expression.Example:__bdata unsigned char byte;int i;if ( __getbit( byte, 3 ) )i = 1;__putbitvoid __putbit( __bit value, operand, bitoffset );42