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chore: modify type signature of util.sext

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This commit is contained in:
Rekai Nyangadzayi Musuka
2022-05-23 12:58:31 -03:00
parent f130d1991c
commit ff3f79801c
5 changed files with 19 additions and 14 deletions
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13
src/util.zig
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@@ -1,11 +1,16 @@
const std = @import("std");
const Log2Int = std.math.Log2Int;
pub inline fn sext(comptime bits: comptime_int, value: u32) u32 {
comptime std.debug.assert(bits <= 32);
const amount = 32 - bits;
// Sign-Extend value of type `T` to type `U`
pub fn sext(comptime T: type, comptime U: type, value: T) T {
// U must have less bits than T
comptime std.debug.assert(@typeInfo(U).Int.bits <= @typeInfo(T).Int.bits);
return @bitCast(u32, @bitCast(i32, value << amount) >> amount);
const iT = std.meta.Int(.signed, @typeInfo(T).Int.bits);
const ExtU = if (@typeInfo(U).Int.signedness == .unsigned) T else iT;
const shift = @intCast(Log2Int(T), @typeInfo(T).Int.bits - @typeInfo(U).Int.bits);
return @bitCast(T, @bitCast(iT, @as(ExtU, @truncate(U, value)) << shift) >> shift);
}
/// See https://godbolt.org/z/W3en9Eche