Riscv

const Riscv = extern struct {
    /// The numbered general-purpose registers r0 - r31. r0 must be zero.
    x: [32]Gpr,
    pc: Gpr,

    pub const Gpr = if (native_arch.isRiscv64()) u64 else u32;

    pub inline fn current() Riscv {
        var ctx: Riscv = undefined;
        asm volatile (if (Gpr == u64)
                \\ sd zero, 0(t0)
                \\ sd ra, 8(t0)
                \\ sd sp, 16(t0)
                \\ sd gp, 24(t0)
                \\ sd tp, 32(t0)
                \\ sd t0, 40(t0)
                \\ sd t1, 48(t0)
                \\ sd t2, 56(t0)
                \\ sd s0, 64(t0)
                \\ sd s1, 72(t0)
                \\ sd a0, 80(t0)
                \\ sd a1, 88(t0)
                \\ sd a2, 96(t0)
                \\ sd a3, 104(t0)
                \\ sd a4, 112(t0)
                \\ sd a5, 120(t0)
                \\ sd a6, 128(t0)
                \\ sd a7, 136(t0)
                \\ sd s2, 144(t0)
                \\ sd s3, 152(t0)
                \\ sd s4, 160(t0)
                \\ sd s5, 168(t0)
                \\ sd s6, 176(t0)
                \\ sd s7, 184(t0)
                \\ sd s8, 192(t0)
                \\ sd s9, 200(t0)
                \\ sd s10, 208(t0)
                \\ sd s11, 216(t0)
                \\ sd t3, 224(t0)
                \\ sd t4, 232(t0)
                \\ sd t5, 240(t0)
                \\ sd t6, 248(t0)
                \\ jal ra, 1f
                \\1:
                \\ sd ra, 256(t0)
            else
                \\ sw zero, 0(t0)
                \\ sw ra, 4(t0)
                \\ sw sp, 8(t0)
                \\ sw gp, 12(t0)
                \\ sw tp, 16(t0)
                \\ sw t0, 20(t0)
                \\ sw t1, 24(t0)
                \\ sw t2, 28(t0)
                \\ sw s0, 32(t0)
                \\ sw s1, 36(t0)
                \\ sw a0, 40(t0)
                \\ sw a1, 44(t0)
                \\ sw a2, 48(t0)
                \\ sw a3, 52(t0)
                \\ sw a4, 56(t0)
                \\ sw a5, 60(t0)
                \\ sw a6, 64(t0)
                \\ sw a7, 68(t0)
                \\ sw s2, 72(t0)
                \\ sw s3, 76(t0)
                \\ sw s4, 80(t0)
                \\ sw s5, 84(t0)
                \\ sw s6, 88(t0)
                \\ sw s7, 92(t0)
                \\ sw s8, 96(t0)
                \\ sw s9, 100(t0)
                \\ sw s10, 104(t0)
                \\ sw s11, 108(t0)
                \\ sw t3, 112(t0)
                \\ sw t4, 116(t0)
                \\ sw t5, 120(t0)
                \\ sw t6, 124(t0)
                \\ jal ra, 1f
                \\1:
                \\ sw ra, 128(t0)
            :
            : [ctx] "{t0}" (&ctx),
            : .{ .x1 = true, .memory = true });
        return ctx;
    }

    pub fn getFp(ctx: *const Riscv) usize {
        return ctx.x[8];
    }
    pub fn getPc(ctx: *const Riscv) usize {
        return ctx.pc;
    }

    pub fn dwarfRegisterBytes(ctx: *Riscv, register_num: u16) DwarfRegisterError![]u8 {
        switch (register_num) {
            0...31 => return @ptrCast(&ctx.x[register_num]),
            65 => return @ptrCast(&ctx.pc),

            32...63 => return error.UnsupportedRegister, // f0 - f31
            64 => return error.UnsupportedRegister, // Alternate Frame Return Column
            96...127 => return error.UnsupportedRegister, // v0 - v31
            3072...4095 => return error.UnsupportedRegister, // Custom extensions
            4096...8191 => return error.UnsupportedRegister, // CSRs

            else => return error.InvalidRegister,
        }
    }
}