Zig on AVR demo

gpio.zig

const Direction = packed enum (u1) {
  Output = 0,
  Input = 1,
};

const Level = packed enum(u1) {
  Low = 0,
  High = 1,
};

const Bit = packed enum(u8) {
  _0 = 1, 
  _1 = 1 << 1, 
  _2 = 1 << 2, 
  _3 = 1 << 3, 
  _4 = 1 << 4, 
  _5 = 1 << 5, 
  _6 = 1 << 6, 
  _7 = 1 << 7, 
};

const GPIO = packed struct {
  input: u8,
  direction: u8,
  output: u8,

  pub fn setDirection(self: *volatile GPIO, bit: Bit, comptime direction: Direction) void {
    switch (direction) {
      Direction.Input => self.direction &= ~@enumToInt(bit), // TODO: Fix
      Direction.Output =>  self.direction |= @enumToInt(bit),
    }
  }

  pub fn write(self: *volatile GPIO, bit: Bit, level: Level) void {
    switch (level) {
      Level.Low => self.output &= ~@enumToInt(bit), // TODO: Fix
      Level.High => self.output |= @enumToInt(bit), // TODO: Fix
    }
  }

  pub fn read(self: *volatile GPIO, bit: Bit) Level {
    return @intToEnum(Level, @boolToInt((self.input & @enumToInt(bit)) != 0));
  }
};

const GPIOB = @intToPtr(*volatile GPIO, 0x23); // TODO: Volatile

export fn main() noreturn {
  GPIOB.setDirection(Bit._1, Direction.Input);
  GPIOB.setDirection(Bit._2, Direction.Output);
  GPIOB.write(Bit._2, Level.High);

  const input = GPIOB.read(Bit._1);

  GPIOB.write(Bit._2, input);

  while (true) {}
}

zig-avr-objdump

gpio.o:     file format elf32-avr


Disassembly of section .text:

00000000 <main>:
   0:	21 98       	cbi	0x04, 1	; 4
   2:	22 9a       	sbi	0x04, 2	; 4
   4:	2a 9a       	sbi	0x05, 2	; 5
   6:	83 b1       	in	r24, 0x03	; 3
   8:	88 0f       	add	r24, r24
   a:	84 70       	andi	r24, 0x04	; 4
   c:	95 b1       	in	r25, 0x05	; 5
   e:	9b 7f       	andi	r25, 0xFB	; 251
  10:	98 2b       	or	r25, r24
  12:	95 b9       	out	0x05, r25	; 5
  14:	00 c0       	rjmp	.+0      	; 0x16 <main+0x16>