Question

Could someone explain how to use Interrupts in C?

I really do not understand it

Answer 1

The C Runtime Library provides function for supporting interrupts service routines written C. These functions install your C function as the interrupt handler for the designated interrupt

HARDWARE INTERRUPTS

There are two types of interrupts that are supported in the ADSP-21xxx processors. The type used by most applications are the hardware interrupts. These interrupts are supported in hardware on the processor. The ADSP-21020 supports these hardware interrupts:

SIG_SOVF Loop stack, status stack overflow interrupt

SIG_TMZ0 Timer (high priority) expired interrupt

SIG_IRQ3 Interrupt 3

SIG_IRQ2 Interrupt 2

SIG_IRQ1 Interrupt 1

SIG_IRQ0 Interrupt 0

SIG_CB7 DAG7 circular buffer overflow interrupt

SIG_CB15 DAG15 circular buffer overflow interrupt

SIG_TMZ Timer (low priority) expired interrupt

SIG_FIX Fixed-point overflow interrupt

SIG_FLTO Floating-point overflow interrupt

SIG_FLTU Floating-point underflow interrupt

SIG_FTLI Floating-point invalid operation interrupt

t SIG_USR0 User interrupt 0

SIG_USR1 User interrupt 1

SIG_USR2 User interrupt 2

SIG_USR3 User interrupt 3

SIG_USR4 User interrupt 4

SIG_USR5 User interrupt 5

SIG_USR6 User interrupt 6

SIG_USR7 User interrupt 7

C Program to Demonstrate use of Interrupts in C Programming

• Interrupts are messages to the Pentium chip to halt it current activity, and perform our requested job.
• We can almost do anything using interrupts without using functions.

• #include<dos.h>

  void main() {

     char *message = "Pritesh Taral$";

     _AH = 9;

     _DX = (int) message;

     geninterrupt(0x21);

  }

  Note below example – we haven’t used printf() still we are able to print message on screen.

• Output:

• Prtesh Taral

• Explanation of Program :

  #include<dos.h>

• dos.h header file contain geninterrupt() function which is used to create interrupt.
• geninterrupt(0x21) is used to generate 0x21 interrupt.
• Note that the sentence is ended with a ‘$’ which is a terminating character.
• geninterrupt(0x21) means that we want to generate the 0x21 interrupt.
• The ‘0x’ prefix is given which tells that the number is in hexadecimal.
• There are many interrupts, each having its own unique number.