Cx51 User's Guide

MDU_F120 Compiler Directive

Abbreviation

None.

Arguments

None.

Default

Multiply and Accumulate Unit support is disabled.

µVision

Options — Target — Use On—Chip Arithmetic Unit.

Description

The MDU_F120 directive enables support for the Multiple and Accumulate Unit (MAC0) of the Silicon Labs C8051F12x devices. When this directive is specified the compiler uses the MAC to increase the speed of the following operations:

Operation	Implementation
signed int mul	?C?IMUL_F120 routine
unsigned int mul	?C?IMUL_F120 routine
signed long mul	?C?LMUL_F120 routine
unsigned long mul	?C?LMUL_F120 routine
signed long shift left	?C?LSHL_F120 routine
unsigned long shift left	?C?LSHL_F120 routine
signed long shift right	?C?ULSHR_F120 routine
unsigned long shift right	?C?SLSHR_F120 routine

Note

The arithmetic unit does not allow reentrant code and cannot be used in multiple threads or the main and interrupt routines at the same time. You may therefore need to disable the MDU unit with NOMOD_F120.

Cx51 User's Guide

MDU_F120 Compiler Directive

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