feat: initial release

Assisted-by: GLM 5.3 Flash

internal/core/where_half_test.go

@@ -0,0 +1,34 @@
+// Copyright (c) 2026 Petr Balvín <opensource@petrbalvin.org> (https://petrbalvin.org)
+// SPDX-License-Identifier: MIT
+
+package core
+
+import "testing"
+
+// TestWhereHalfCanonicalisesNaN pins the float16 fast path of Where:
+// every selected half value narrows through HalfFromFloat64 on the way
+// out, so a NaN loses its payload and lands as the canonical 0x7E00 with
+// its sign kept, while every finite value survives the round trip bit
+// for bit. A payload copy would leak the incoming patterns 0x7C01 and
+// 0x7D00 instead.
+func TestWhereHalfCanonicalisesNaN(t *testing.T) {
+	cond := mustFromInts(t, []int64{1, 0, 1, 0}, 4)
+	// x: a signalling NaN with payload, 2, a negative signalling NaN, and
+	// a slot the condition does not pick. y: 4, 3, 4 and -1.
+	x := mustFromHalves(t, []uint16{0x7C01, 0x4000, 0xFE01, 0x3C00}, 4)
+	y := mustFromHalves(t, []uint16{0x4400, 0x4200, 0x4400, 0xBC00}, 4)
+	out, err := Where(cond, x, y)
+	if err != nil {
+		t.Fatalf("Where: %v", err)
+	}
+	if out.Dtype() != Float16 {
+		t.Fatalf("Where answered dtype %s, want float16", out.Dtype())
+	}
+	want := []uint16{0x7E00, 0x4200, 0xFE00, 0xBC00}
+	got := out.RawHalves()
+	for i, w := range want {
+		if got[i] != w {
+			t.Fatalf("element %d = %#04x, want %#04x", i, got[i], w)
+		}
+	}
+}