Sign-Extension and Zero-Extension Helpers in Odin

bit_extension.odin

package bit_extension

import "core:intrinsics"

sign_extend :: #force_inline proc "contextless" ($D: typeid, src: $S) -> D where
    intrinsics.type_is_integer(D) &&
    intrinsics.type_is_integer(S) &&
    size_of(D) >= size_of(S)
{
    when size_of(S) == size_of(i128) {
        when      size_of(D) == size_of(i128) do return D(src)
    }
    else when size_of(S) == size_of(i64) {
        when      size_of(D) == size_of(i128) do return D(i128(i64(src)))
        else when size_of(D) == size_of(i64)  do return D(src)
    }
    else when size_of(S) == size_of(i32) {
        when      size_of(D) == size_of(i128) do return D(i128(i32(src)))
        else when size_of(D) == size_of(i64)  do return D(i64(i32(src)))
        else when size_of(D) == size_of(i32)  do return D(src)
    }
    else when size_of(S) == size_of(i16) {
        when      size_of(D) == size_of(i128) do return D(i128(i16(src)))
        else when size_of(D) == size_of(i64)  do return D(i64(i16(src)))
        else when size_of(D) == size_of(i32)  do return D(i32(i16(src)))
        else when size_of(D) == size_of(i16)  do return D(src)
    }
    else when size_of(S) == size_of(i8) {
        when      size_of(D) == size_of(i128) do return D(i128(i8(src)))
        else when size_of(D) == size_of(i64)  do return D(i64(i8(src)))
        else when size_of(D) == size_of(i32)  do return D(i32(i8(src)))
        else when size_of(D) == size_of(i16)  do return D(i16(i8(src)))
        else when size_of(D) == size_of(i8)   do return D(src)
    }
    else do #panic("unreachable")
}

zero_extend :: #force_inline proc "contextless" ($D: typeid, src: $S) -> D where
    intrinsics.type_is_integer(D) &&
    intrinsics.type_is_integer(S) &&
    size_of(D) >= size_of(S)
{
    when size_of(S) == size_of(u128) {
        when      size_of(D) == size_of(u128) do return D(src)
    }
    else when size_of(S) == size_of(u64) {
        when      size_of(D) == size_of(u128) do return D(u128(u64(src)))
        else when size_of(D) == size_of(u64)  do return D(src)
    }
    else when size_of(S) == size_of(u32) {
        when      size_of(D) == size_of(u128) do return D(u128(u32(src)))
        else when size_of(D) == size_of(u64)  do return D(u64(u32(src)))
        else when size_of(D) == size_of(u32)  do return D(src)
    }
    else when size_of(S) == size_of(u16) {
        when      size_of(D) == size_of(u128) do return D(u128(u16(src)))
        else when size_of(D) == size_of(u64)  do return D(u64(u16(src)))
        else when size_of(D) == size_of(u32)  do return D(u32(u16(src)))
        else when size_of(D) == size_of(u16)  do return D(src)
    }
    else when size_of(S) == size_of(u8) {
        when      size_of(D) == size_of(u128) do return D(u128(u8(src)))
        else when size_of(D) == size_of(u64)  do return D(u64(u8(src)))
        else when size_of(D) == size_of(u32)  do return D(u32(u8(src)))
        else when size_of(D) == size_of(u16)  do return D(u16(u8(src)))
        else when size_of(D) == size_of(u8)   do return D(src)
    }
    else do #panic("unreachable")
}