PicC 9.50 dsPIC Manual.pdf

Library FunctionsDI, EISynopsis#include EI ()DI ()DescriptionThe DI() and EI() routines disable and re-enable interrupts respectively. These are implemented asmacros defined in dsPIC.h. The example shows the use of EI() and EI() around access to a longvariable that is modified during an interrupt. If this was not done, it would be possible to return anincorrect value, if the interrupt occurred between accesses to successive words of the count value.Example#include long count;voidinterrupt void tick (void) @ T1_VCTR{count++;}longgetticks (void){long val;}DI();val = count;EI();return val;/* Disable interrupts around accessto count, to ensure consistency.*/140