updated downloader

scripts/test_grib_read.go

@@ -0,0 +1,38 @@
+package main
+
+import (
+	"fmt"
+	"os"
+
+	"github.com/nilsmagnus/grib/griblib"
+)
+
+func main() {
+	f, err := os.Open("C:/tmp/grib/gfs.t18z.pgrb2.0p25.f000")
+	if err != nil {
+		fmt.Printf("Error opening file: %v\n", err)
+		return
+	}
+	defer f.Close()
+
+	messages, err := griblib.ReadMessages(f)
+	if err != nil {
+		fmt.Printf("Error reading GRIB: %v\n", err)
+		return
+	}
+
+	fmt.Printf("Found %d messages\n\n", len(messages))
+
+	for i, m := range messages {
+		product := m.Section4.ProductDefinitionTemplate
+		if product.ParameterCategory != 2 || product.ParameterNumber != 2 {
+			continue // only u-wind
+		}
+		fmt.Printf("UGRD Msg %d: SurfType=%d SurfValue=%d SurfScale=%d DataLen=%d\n",
+			i,
+			product.FirstSurface.Type,
+			product.FirstSurface.Value,
+			product.FirstSurface.Scale,
+			len(m.Data()))
+	}
+}