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Introduction

PeakRDL-halcpp is a free and open-source C++ (HAL) Hardware Abstraction Layer generator. The tool converts a SystemRDL description into a C++ low level HAL drivers. Generated drivers are meant to be used for interfacing the registers in the IP block, usually by a CPU connected to the peripheral through a bus.

  • Generated drivers are based on C++17 standard
  • The size and performance of the compiled binary is the same as equivalent C drivers
  • Generated drivers preserve the hierarchy of the source SystemRDL description, composing a C++ template class based hierarchy
  • Use only embedded friendly parts of the C++ standard to be suitable for resource constrained environments like microcontrollers

Features​

Some of the features that are available within the drivers:

Assignment and conversion operators​

Assignment and conversion operators are provided for Fields and Registers in order to have a nicer and more readable code.
It is possible to write code like this:

soc.gpio0.ODR = 0xff;
uint32_t in_data = soc.gpio0.IDR;

An equivalent code without using the operators would be:

soc.gpio0.ODR.set(0xff);
uint32_t in_data = soc.gpio0.IDR.get();

Constants and enumerations​

There is a Const type that provides a compile time constant. On top of Const class enumerations are constructed from the SystemRDL description.

The Const class also provides a concatenation with , (comma) operator, so its possible to assign value to a register like this:

soc.gpio0.CFG0 = (pincfg::IN, pincfg::OUT, pincfg::OUT_PP, pincfg::OUT_OD);

The goal is to avoid magical numbers in your code, which can look like this:

soc.gpio0.CFG0 = 0x123456;

In previous case CFG0 is a 24-bit register and pincfg is a 3-bit enum, so the total number of bits in the concatenation will amount to 12, this will cause a compilation error. It is by default strongly typed and does not allow width mismatch. To solve this in previous example, it is necessary to pad the list with Const, like this:

soc.gpio0.CFG0 = (Const<12, 0>(), pincfg::IN, pincfg::OUT, pincfg::OUT_PP, pincfg::OUT_OD);

Const is the template that the other enums are built from, and its parameters are Const<WIDTH, VAL>