1 files changed, 95 insertions, 0 deletions
diff --git a/src/op/br_if.c b/src/op/br_if.c
new file mode 100644
index 0000000..661c959
--- /dev/null
+++ b/src/op/br_if.c
@@ -0,0 +1,95 @@
+/*
+ * nanowasm, a tiny WebAssembly/Wasm interpreter
+ * Copyright (C) 2023-2025  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 <nanowasm/nw.h>
+#include <nw/interp.h>
+#include <nw/io.h>
+#include <nw/log.h>
+#include <nw/ops.h>
+#include <nw/routines.h>
+#include <nw/stack.h>
+#include <nw/types.h>
+
+static int condition(struct nw_interp *const i)
+{
+    const struct nw_i_sm_br_if *const b = &i->sm.br_if;
+
+    switch (i->push_type)
+    {
+        case NW_TYPE_I32:
+            return b->condition.i32;
+
+        case NW_TYPE_I64:
+            return b->condition.i64.low;
+
+        case NW_TYPE_F32:
+            return b->condition.f32;
+
+        case NW_TYPE_F64:
+            return b->condition.f64;
+    }
+
+    return 0;
+}
+
+static enum nw_state pop(struct nw_interp *const i)
+{
+    struct nw_i_sm_br_if *const b = &i->sm.br_if;
+    const enum nw_state n = nwp_stack_pop(i, &b->io);
+
+    if (n)
+        return n;
+    else if (condition(i))
+        nwp_break(i, b->relative_depth);
+    else
+        nwp_interp_resume(i);
+
+    return NW_AGAIN;
+}
+
+static enum nw_state get_relative_depth(struct nw_interp *const i)
+{
+    struct nw_i_sm_br_if *const b = &i->sm.br_if;
+    const struct nw_io_cfg *const cfg = &i->cfg.io;
+    const enum nw_state n = nwp_varuint32(cfg, &b->leb128,
+        &b->relative_depth, cfg->user);
+    size_t sz;
+
+    if (n)
+        return n;
+    else if (nwp_type_sz(i->push_type, &sz))
+    {
+        static const char *const exc = "invalid type";
+
+        i->exception = exc;
+#ifdef NW_LOG
+        nwp_log("%s: %#x\n", exc, (unsigned)i->push_type);
+#endif
+        return NW_FATAL;
+    }
+    else
+    {
+        struct nw_sm_io io = {0};
+
+        io.buf = &b->condition;
+        io.n = sz;
+        b->io = io;
+        i->next = pop;
+    }
+
+    return NW_AGAIN;
+}
+
+void nwp_op_br_if(struct nw_interp *const i)
+{
+    static const struct nw_i_sm_br_if b = {0};
+
+    i->next = get_relative_depth;
+    i->sm.br_if = b;
+}