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fix(math): eval isPowerOfTwo at comptime in rotl/rotr

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paoda 2024-03-09 04:46:43 -06:00 committed by Veikka Tuominen
parent d565c5dfcd
commit a4508ad716
1 changed files with 8 additions and 6 deletions
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14
lib/std/math.zig
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@ -682,15 +682,15 @@ pub fn rotr(comptime T: type, x: T, r: anytype) T {
if (@typeInfo(C).Int.signedness == .signed) {
@compileError("cannot rotate signed integers");
}
const ar = @as(Log2Int(C), @intCast(@mod(r, @typeInfo(C).Int.bits)));
const ar: Log2Int(C) = @intCast(@mod(r, @typeInfo(C).Int.bits));
return (x >> @splat(ar)) | (x << @splat(1 + ~ar));
} else if (@typeInfo(T).Int.signedness == .signed) {
@compileError("cannot rotate signed integer");
} else {
if (T == u0) return 0;
if (isPowerOfTwo(@typeInfo(T).Int.bits)) {
const ar = @as(Log2Int(T), @intCast(@mod(r, @typeInfo(T).Int.bits)));
if (comptime isPowerOfTwo(@typeInfo(T).Int.bits)) {
const ar: Log2Int(T) = @intCast(@mod(r, @typeInfo(T).Int.bits));
return x >> ar | x << (1 +% ~ar);
} else {
const ar = @mod(r, @typeInfo(T).Int.bits);
@ -713,6 +713,7 @@ test "rotr" {
try testing.expect(rotr(u8, 0b00000001, @as(usize, 8)) == 0b00000001);
try testing.expect(rotr(u8, 0b00000001, @as(usize, 4)) == 0b00010000);
try testing.expect(rotr(u8, 0b00000001, @as(isize, -1)) == 0b00000010);
try testing.expect(rotr(u12, 0o7777, 1) == 0o7777);
try testing.expect(rotr(@Vector(1, u32), @Vector(1, u32){1}, @as(usize, 1))[0] == @as(u32, 1) << 31);
try testing.expect(rotr(@Vector(1, u32), @Vector(1, u32){1}, @as(isize, -1))[0] == @as(u32, 1) << 1);
}
@ -727,15 +728,15 @@ pub fn rotl(comptime T: type, x: T, r: anytype) T {
if (@typeInfo(C).Int.signedness == .signed) {
@compileError("cannot rotate signed integers");
}
const ar = @as(Log2Int(C), @intCast(@mod(r, @typeInfo(C).Int.bits)));
const ar: Log2Int(C) = @intCast(@mod(r, @typeInfo(C).Int.bits));
return (x << @splat(ar)) | (x >> @splat(1 +% ~ar));
} else if (@typeInfo(T).Int.signedness == .signed) {
@compileError("cannot rotate signed integer");
} else {
if (T == u0) return 0;
if (isPowerOfTwo(@typeInfo(T).Int.bits)) {
const ar = @as(Log2Int(T), @intCast(@mod(r, @typeInfo(T).Int.bits)));
if (comptime isPowerOfTwo(@typeInfo(T).Int.bits)) {
const ar: Log2Int(T) = @intCast(@mod(r, @typeInfo(T).Int.bits));
return x << ar | x >> 1 +% ~ar;
} else {
const ar = @mod(r, @typeInfo(T).Int.bits);
@ -758,6 +759,7 @@ test "rotl" {
try testing.expect(rotl(u8, 0b00000001, @as(usize, 8)) == 0b00000001);
try testing.expect(rotl(u8, 0b00000001, @as(usize, 4)) == 0b00010000);
try testing.expect(rotl(u8, 0b00000001, @as(isize, -1)) == 0b10000000);
try testing.expect(rotl(u12, 0o7777, 1) == 0o7777);
try testing.expect(rotl(@Vector(1, u32), @Vector(1, u32){1 << 31}, @as(usize, 1))[0] == 1);
try testing.expect(rotl(@Vector(1, u32), @Vector(1, u32){1 << 31}, @as(isize, -1))[0] == @as(u32, 1) << 30);
}