//! The floor: the smallest thing that can boot on this chip and prove it is alive.
//! No printing, no descriptor text - just a pin that toggles. Build it with
//!   zig build -Dapp=examples/minimal.zig size

const std = @import("std");
const config = @import("config");
const soc = @import("soc");

/// Even the floor needs a panic handler: the default one formats and would pull in half of std.
pub const panic = std.debug.FullPanic(struct {
    fn call(_: []const u8, _: ?usize) noreturn {
        while (true) {}
    }
}.call);
const led: u6 = @intCast(config.led_pin);

export fn zig_main() noreturn {
    soc.gpio.configureOutput(led, .{});
    while (true) {
        soc.gpio.setHigh(led);
        soc.rom.ets_delay_us(100_000);
        soc.gpio.setLow(led);
        soc.rom.ets_delay_us(100_000);
    }
}

export fn _start() linksection(".text.entry") callconv(.naked) noreturn {
    asm volatile (
        \\ li t0, 1 << 13
        \\ csrs mstatus, t0
        \\ la sp, __stack_top
        \\ la t0, __bss_start
        \\ la t1, __bss_end
        \\ bgeu t0, t1, 2f
        \\1:
        \\ sw zero, 0(t0)
        \\ addi t0, t0, 4
        \\ bltu t0, t1, 1b
        \\2:
        \\ j zig_main
    );
}