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Jacqueline

Jacqueline is an experimental bootloader written in Pascal (Free Pascal dialect) written for the i386 architecture, just because. Note that, unlike NativeOS, I have no plans to further develop Jacqueline once the system compiles and I'm able to start the image using an emulator.

Why Pascal?

Even while Pascal wasn't written with low-level programming in mind, it is nonetheless possible to do low-level systems programming with the Free Pascal dialect, as it supports features that are present in other low-level languages such as C, C++ or even Rust in unsafe mode, such as:

  • Pointers, using the ^ operator (such as var intptr: ^integer).
  • Memory addresses, using the @ operator (let var foo: integer, then @foo yields the memory address of foo as an ^integer.
  • Inline assembly interfacing, through the asm keyword, à la C. In fact, I find more intuitive to move data between registers and variables in Free Pascal than in GNU C.

Free Pascal is able to generate standard object files (*.o), encoded in popular executable file formats such as PE and ELF, and thus, it is possible to make object files written originally in diverse languages such as C, Pascal or Assembly to interface each other.

Setting up

Requirements

  • An i386-elf toolchain (required for compiling the Assembly code and linking the final kernel image).
  • A Free Pascal distribution with 32 bit support (i.e., ppc386 is provided).
  • BSD make or GNU make.
  • QEMU to run the kernel.

How to

make qemu