The Small Device C Compiler (SDCC) is a popular open-source compiler for embedded systems and microcontrollers. It supports a wide range of microcontrollers, and provides various compiler-specific extensions to enhance the capabilities of the C++ programming language. In this article, we will explore some of the most useful SDCC compiler-specific extensions in C++.

1. Inline Assembly

SDCC provides support for inline assembly, which allows you to embed assembly code directly within your C++ source code. This enables you to have fine-grained control over the low-level hardware operations and utilize architecture-specific features. To use inline assembly in SDCC, you can use the __asm__ keyword followed by the assembly code, enclosed in a pair of double underscores.

int get_processor_id() {
   int processor_id;
   __asm__("mov r0,#0x01\n"
           "mov %0,r0" : "=r" (processor_id));
   return processor_id;
}

In the above example, the inline assembly code retrieves the processor ID and stores it in the processor_id variable using the mov instruction.

2. Bit-Level Access

SDCC provides compiler-specific extensions to access individual bits of a byte or word, which can be handy when working with hardware registers or bit manipulation. SDCC allows you to define and access individual bits using the __bit data type and the __sbit data type for signed bits.

__bit flag = 0;

__sbit signed_flag = 0;

int main() {
   // Accessing a bit
   flag = 1;

   // Accessing a signed bit
   signed_flag = 1;

   // Checking the state of a bit
   if (flag) {
       // Do something
   }

   // Checking the state of a signed bit
   if (signed_flag) {
       // Do something
   }

   return 0;
}

In the above example, the flag variable is defined as a single bit and can be manipulated using simple assignment. The signed_flag variable is defined as a signed bit and follows the same rules.

These are just a few of the SDCC compiler-specific extensions available in C++. By leveraging these extensions, you can write more efficient and optimized code targeting specific microcontrollers and embedded systems.

#programming #embedded #SDCC #compilerextensions