src/startup.zig


1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41

const main = @import("main.zig");

extern const __data_flash: u32;
extern const __data: u32;
extern const __data_size: u32;
extern const __bss: u32;
extern const __bss_size: u32;

comptime {
    asm (
        \\.extern _start
        \\.extern _tstack
        \\
        \\.section .vector_table
        \\.global init_vector_table
        \\init_vector_table:
        \\    .word _tstack
        \\    .word _start
        \\    .skip 4 * 14
    );
}

inline fn zero_bss() void {
    const bss: [*]volatile u8 = @ptrFromInt(@intFromPtr(&__bss));
    @memset(bss[0..@intFromPtr(&__bss_size)], 0);
}

inline fn copy_data() void {
    const data_flash: [*]volatile u8 = @ptrFromInt(@intFromPtr(&__data_flash));
    const data: [*]volatile u8 = @ptrFromInt(@intFromPtr(&__data));
    const data_size = @intFromPtr(&__data_size);
    @memcpy(data[0..data_size], data_flash[0..data_size]);
}

export fn _start() callconv(.C) noreturn {
    zero_bss();
    copy_data();
    main.main();
    while (true) {}
}