Alpha

const Alpha = extern struct {
    /// The numbered general-purpose registers R0 - R31.
    r: [32]Gpr,
    pc: Gpr,

    pub const Gpr = u64;

    pub inline fn current() Alpha {
        var ctx: Alpha = undefined;
        asm volatile (
            \\ stq $0 , 0x000($0)
            \\ stq $1 , 0x008($0)
            \\ stq $2 , 0x010($0)
            \\ stq $3 , 0x018($0)
            \\ stq $4 , 0x020($0)
            \\ stq $5 , 0x028($0)
            \\ stq $6 , 0x030($0)
            \\ stq $7 , 0x038($0)
            \\ stq $8 , 0x040($0)
            \\ stq $9 , 0x048($0)
            \\ stq $10, 0x050($0)
            \\ stq $11, 0x058($0)
            \\ stq $12, 0x060($0)
            \\ stq $13, 0x068($0)
            \\ stq $14, 0x070($0)
            \\ stq $15, 0x078($0)
            \\ stq $16, 0x080($0)
            \\ stq $17, 0x088($0)
            \\ stq $18, 0x090($0)
            \\ stq $19, 0x098($0)
            \\ stq $20, 0x0a0($0)
            \\ stq $21, 0x0a8($0)
            \\ stq $22, 0x0b0($0)
            \\ stq $23, 0x0b8($0)
            \\ stq $24, 0x0c0($0)
            \\ stq $25, 0x0c8($0)
            \\ stq $26, 0x0d0($0)
            \\ stq $27, 0x0d8($0)
            \\ stq $28, 0x0e0($0)
            \\ stq $29, 0x0e8($0)
            \\ stq $30, 0x0f0($0)
            \\ stq $31, 0x0f8($0)
            \\
            \\ br $1, 1f
            \\1:
            \\ stq $1, 0x100($0)
            :
            : [ctx] "{$0}" (&ctx),
            : .{ .r1 = true, .memory = true });
        return ctx;
    }

    pub fn getFp(ctx: *const Alpha) usize {
        return ctx.r[15];
    }
    pub fn getPc(ctx: *const Alpha) usize {
        return ctx.pc;
    }

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

            32...63 => return error.UnsupportedRegister, // f0 - f31
            66 => return error.UnsupportedRegister, // uniq

            else => return error.InvalidRegister,
        }
    }
}