You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
104 lines
2.7 KiB
Zig
104 lines
2.7 KiB
Zig
const std = @import("std");
|
|
const microzig = @import("microzig");
|
|
const root = @import("root");
|
|
|
|
pub const StatusRegister = enum(u8) {
|
|
// machine information
|
|
mvendorid,
|
|
marchid,
|
|
mimpid,
|
|
mhartid,
|
|
|
|
// machine trap setup
|
|
mstatus,
|
|
misa,
|
|
mtvec,
|
|
};
|
|
|
|
pub inline fn setStatusBit(comptime reg: StatusRegister, bits: u32) void {
|
|
asm volatile ("csrrs zero, " ++ @tagName(reg) ++ ", %[value]"
|
|
:
|
|
: [value] "r" (bits),
|
|
);
|
|
}
|
|
|
|
pub inline fn clearStatusBit(comptime reg: StatusRegister, bits: u32) void {
|
|
asm volatile ("csrrc zero, " ++ @tagName(reg) ++ ", %[value]"
|
|
:
|
|
: [value] "r" (bits),
|
|
);
|
|
}
|
|
|
|
pub inline fn disable_interrupts() void {
|
|
clearStatusBit(.mstatus, 0x08);
|
|
}
|
|
|
|
pub inline fn enable_interrupts() void {
|
|
setStatusBit(.mstatus, 0x08);
|
|
}
|
|
|
|
pub const startup_logic = struct {
|
|
comptime {
|
|
// See this:
|
|
// https://github.com/espressif/esp32c3-direct-boot-example
|
|
|
|
// Direct Boot: does not support Security Boot and programs run directly in flash. To enable this mode, make
|
|
// sure that the first two words of the bin file downloading to flash (address: 0x42000000) are 0xaedb041d.
|
|
|
|
// In this case, the ROM bootloader sets up Flash MMU to map 4 MB of Flash to
|
|
// addresses 0x42000000 (for code execution) and 0x3C000000 (for read-only data
|
|
// access). The bootloader then jumps to address 0x42000008, i.e. to the
|
|
// instruction at offset 8 in flash, immediately after the magic numbers.
|
|
|
|
asm (
|
|
\\.extern _start
|
|
\\.section microzig_flash_start
|
|
\\.align 4
|
|
\\.byte 0x1d, 0x04, 0xdb, 0xae
|
|
\\.byte 0x1d, 0x04, 0xdb, 0xae
|
|
);
|
|
}
|
|
|
|
extern fn microzig_main() noreturn;
|
|
|
|
export fn _start() linksection("microzig_flash_start") callconv(.C) noreturn {
|
|
microzig.cpu.disable_interrupts();
|
|
asm volatile ("mv sp, %[eos]"
|
|
:
|
|
: [eos] "r" (@as(u32, microzig.config.end_of_stack)),
|
|
);
|
|
asm volatile ("la gp, __global_pointer$");
|
|
microzig.cpu.setStatusBit(.mtvec, microzig.config.end_of_stack);
|
|
root.initialize_system_memories();
|
|
microzig_main();
|
|
}
|
|
|
|
export fn _rv32_trap() callconv(.C) noreturn {
|
|
while (true) {}
|
|
}
|
|
|
|
const vector_table = [_]fn () callconv(.C) noreturn{
|
|
_rv32_trap,
|
|
_rv32_trap,
|
|
_rv32_trap,
|
|
_rv32_trap,
|
|
_rv32_trap,
|
|
_rv32_trap,
|
|
_rv32_trap,
|
|
_rv32_trap,
|
|
_rv32_trap,
|
|
_rv32_trap,
|
|
_rv32_trap,
|
|
_rv32_trap,
|
|
_rv32_trap,
|
|
_rv32_trap,
|
|
_rv32_trap,
|
|
_rv32_trap,
|
|
_rv32_trap,
|
|
_rv32_trap,
|
|
_rv32_trap,
|
|
_rv32_trap,
|
|
_rv32_trap,
|
|
};
|
|
};
|