First commit

1 files changed, 95 insertions, 0 deletions

diff --git a/src/op/control_flow/br_if.c b/src/op/control_flow/br_if.c
new file mode 100644
index 0000000..25bfdee
--- /dev/null
+++ b/src/op/control_flow/br_if.c
@@ -0,0 +1,95 @@
+/*
+ * 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 branch(struct nw_interp *const i, const varuint32 relative_depth)
+{
+    const struct nw_block *b = i->fp->last_block;
+    static const char exc[] = "relative depth and block count mismatch";
+
+    for (varuint32 d = 0; b && d < relative_depth; d++)
+        b = b->prev;
+
+    if (!b)
+    {
+        LOG("%s: %s\n", __func__, exc);
+        i->exception = exc;
+        return -1;
+    }
+
+    if (fseek(i->f, b->pc, SEEK_SET))
+    {
+        LOG("%s: fseek(3): %s\n", __func__, strerror(errno));
+        i->exception = "I/O error";
+        return -1;
+    }
+
+    return 0;
+}
+
+static bool cond(struct nw_interp *const i)
+{
+    int32_t value;
+
+    if (interp_stack_pop(i, &value, sizeof value))
+    {
+        LOG("%s: interp_stack_pop failed\n", __func__);
+        return -1;
+    }
+
+    return value;
+}
+
+static int br_if(struct nw_interp *const i, const varuint32 relative_depth)
+{
+    if (cond(i) && branch(i, relative_depth))
+    {
+        LOG("%s: branch failed\n", __func__);
+        return -1;
+    }
+
+    return 0;
+}
+
+static int op(struct nw_interp *const i, FILE *const f)
+{
+    varuint32 relative_depth;
+
+    if (varuint32_read(f, &relative_depth))
+    {
+        LOG("%s: varuint32_read failed\n", __func__);
+        return 1;
+    }
+    else if (i && br_if(i, relative_depth))
+    {
+        LOG("%s: br_if failed\n", __func__);
+        return -1;
+    }
+
+    return 0;
+}
+
+int op_br_if(struct nw_interp *const i)
+{
+    return op(i, i->f);
+}
+
+int check_br_if(FILE *const f)
+{
+    return op(NULL, f);
+}