Initial project import

tools/v/examples/sha256sum_with_io_cp.v

@@ -0,0 +1,28 @@
+// This example shows how to use io.cp, in combination with os.open and crypto.sha256,
+// to read and hash files chunk by chunk, without loading them completely in memory (which may
+// require too much RAM with big files).
+//
+// Usage: examples/sha256sum_with_io_cp [FILE]...
+//
+// Note: to compile the program, use:
+// `v -prod -cflags "-march=native -mtune=native" examples/sha256sum_with_io_cp.v`
+// After that, to compare it with say `sha256sum`, you can run:
+// `v repeat -R 5 "sha256sum v" "examples/sha256sum_with_io_cp v`
+import os
+import io
+import crypto.sha256
+
+fn hash_file(path string) !string {
+	mut file := os.open(path)!
+	mut digest := sha256.new()
+	io.cp(mut file, mut digest, buffer_size: 256 * 1024)!
+	file.close()
+	return digest.sum([]).hex()
+}
+
+fn main() {
+	for fpath in os.args#[1..] {
+		h := hash_file(fpath)!
+		println('${h}  ${fpath}')
+	}
+}