1 files changed, 75 insertions, 0 deletions
diff --git a/src/op/control_flow/block.c b/src/op/control_flow/block.c
new file mode 100644
index 0000000..56f72f1
--- /dev/null
+++ b/src/op/control_flow/block.c
@@ -0,0 +1,75 @@
+/*
+ * nanowasm, a tiny WebAssembly/Wasm interpreter
+ * Copyright (C) 2023-2024  Xavier Del Campo Romero
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/.
+ */
+
+#include <nw/log.h>
+#include <nw/ops.h>
+#include <nanowasm/nw.h>
+#include <nw/interp.h>
+#include <nw/types.h>
+#include <errno.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <string.h>
+
+static int push(struct nw_interp *const i, FILE *const f)
+{
+    const long pc = ftell(f);
+
+    if (pc < 0)
+    {
+        LOG("%s: ftell(3): %s\n", __func__, strerror(errno));
+        i->exception = "I/O error";
+        return -1;
+    }
+
+    struct nw_frame *const fp = i->fp;
+    struct nw_block *const p = interp_stackptr(i);
+    const struct nw_block b =
+    {
+        .pc = pc,
+        .prev = fp->last_block
+    };
+
+    if (interp_stack_push(i, &b, sizeof b))
+    {
+        LOG("%s: interp_stack_push failed\n", __func__);
+        return -1;
+    }
+
+    fp->last_block = p;
+    return 0;
+}
+
+static int op(struct nw_interp *const i, FILE *const f)
+{
+    varint7 sig;
+
+    if (varint7_read(f, &sig))
+    {
+        LOG("%s: varint7_read failed\n", __func__);
+        return -1;
+    }
+    else if (i && push(i, f))
+    {
+        LOG("%s: push failed\n", __func__);
+        return -1;
+    }
+
+    return 0;
+}
+
+int op_block(struct nw_interp *const i)
+{
+    return op(i, i->f);
+}
+
+int check_block(FILE *const f)
+{
+    return op(NULL, f);
+}