feat: initial release

Assisted-by: GLM 5.3 Flash

io/fitstable_keyword_pin_test.go

@@ -0,0 +1,80 @@
+// Copyright (c) 2026 Petr Balvín <opensource@petrbalvin.org> (https://petrbalvin.org)
+// SPDX-License-Identifier: MIT
+
+package io
+
+import (
+	"encoding/binary"
+	"os"
+	"path/filepath"
+	"testing"
+
+	"sourcedock.dev/petrbalvin/tensor/internal/core"
+)
+
+// The binary-table reader resolves header keywords through a map whose
+// documented rule is first-occurrence-wins, the behaviour the previous
+// linear scan answered. A hostile header may repeat a structural card
+// with a different value: this pin fixes that the reader follows the
+// first value of each repeated card.
+func TestLoadFITSTableRepeatedKeywordsFirstWins(t *testing.T) {
+	body := make([]byte, 16)
+	for r := range 2 {
+		binary.BigEndian.PutUint64(body[r*8:], uint64(1000+r))
+	}
+	cards := []string{
+		fitsStringCardRaw("XTENSION", "BINTABLE"),
+		fitsIntCard("BITPIX", 8),
+		fitsIntCard("NAXIS", 2),
+		fitsIntCard("NAXIS1", 8),
+		fitsIntCard("NAXIS2", 2),
+		fitsIntCard("NAXIS2", 99),
+		fitsIntCard("PCOUNT", 0),
+		fitsIntCard("GCOUNT", 1),
+		fitsIntCard("TFIELDS", 1),
+		fitsIntCard("TFIELDS", 5),
+		fitsStringCardRaw("TTYPE1", "COL1"),
+		fitsStringCardRaw("TFORM1", "K"),
+		fitsStringCardRaw("TFORM1", "D"),
+		fitsEndCard(),
+	}
+	out := fitsAppendCards(nil, []string{
+		fitsBoolCard("SIMPLE", true),
+		fitsIntCard("BITPIX", 8),
+		fitsIntCard("NAXIS", 0),
+		fitsBoolCard("EXTEND", true),
+		fitsEndCard(),
+	})
+	out = fitsAppendCards(out, cards)
+	out = append(out, body...)
+	out = fitsAppendZeroPad(out)
+	path := filepath.Join(t.TempDir(), "repeated.fits")
+	if err := os.WriteFile(path, out, 0o644); err != nil {
+		t.Fatal(err)
+	}
+	table, err := LoadFITSTable(path)
+	if err != nil {
+		t.Fatalf("LoadFITSTable: %v", err)
+	}
+	if table.Rows != 2 {
+		t.Fatalf("rows = %d, want 2 from the first NAXIS2", table.Rows)
+	}
+	if len(table.Columns) != 1 {
+		t.Fatalf("columns = %d, want 1 from the first TFIELDS", len(table.Columns))
+	}
+	col := table.Columns[0]
+	if col == nil {
+		t.Fatal("the first column came back nil; the repeated TFORM1 must still decode the first form")
+	}
+	if len(table.Text) > 0 && table.Text[0] != nil {
+		t.Fatalf("column text = %v, want nil for a K column decoded from the first TFORM1", table.Text[0])
+	}
+	if col.Dtype() != core.Int {
+		t.Fatalf("column dtype = %s, want Int from the first TFORM1 (K)", col.Dtype())
+	}
+	for i, want := range []int64{1000, 1001} {
+		if got := col.RawInts()[i]; got != want {
+			t.Fatalf("value %d = %d, want %d", i, got, want)
+		}
+	}
+}