1 files changed, 100 insertions, 0 deletions
diff --git a/src/routines/find_function.c b/src/routines/find_function.c
new file mode 100644
index 0000000..c0273ec
--- /dev/null
+++ b/src/routines/find_function.c
@@ -0,0 +1,100 @@
+/*
+ * 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 <nanowasm/types.h>
+#include <nw/interp.h>
+#include <nw/io.h>
+#include <nw/log.h>
+#include <nw/routines.h>
+
+static enum nw_state seek_code(struct nw_interp *const i)
+{
+    const struct nw_i_sm_ffn *const f = &i->sm.ffn;
+    const struct nw_io_cfg *const cfg = &i->cfg.io;
+    const unsigned long fbo = nwp_leuint32(&f->fbo);
+    const enum nw_state n = cfg->seek(fbo, cfg->user);
+
+    if (n)
+        return n;
+
+    f->next(i);
+    return NW_AGAIN;
+}
+
+static enum nw_state get_fbo(struct nw_interp *const i)
+{
+    struct nw_i_sm_ffn *const f = &i->sm.ffn;
+    const struct nw_io_cfg *const cfg = &i->cfg.io;
+    const enum nw_state n = nwp_io_read(cfg, &f->io, cfg->user);
+
+    if (n)
+        return n;
+
+    i->next = seek_code;
+    return NW_AGAIN;
+}
+
+static enum nw_state seek_fbo(struct nw_interp *const i)
+{
+    struct nw_i_sm_ffn *const f = &i->sm.ffn;
+    const struct nw_mod *const m = i->cfg.m;
+    long offset = m->c_sections[NW_CUSTOM_FBO];
+    const struct nw_io_cfg *const cfg = &i->cfg.io;
+    enum nw_state n;
+
+    if (!offset)
+    {
+        static const char *const exc = "nw_fbo section not found";
+
+#ifdef NW_LOG
+        nwp_log("%s\n", exc);
+#endif
+        i->exception = exc;
+        return NW_FATAL;
+    }
+    else if (f->fn.index < m->import_count)
+    {
+        static const char *const exc = "invalid function index";
+
+        i->exception = exc;
+#ifdef NW_LOG
+        nwp_log("%s: %lu\n", exc, (unsigned long)f->fn.index);
+#endif
+        return NW_FATAL;
+    }
+
+    offset += sizeof f->fbo * (f->fn.index - m->import_count);
+
+    if ((n = cfg->seek(offset, cfg->user)))
+        return n;
+    else
+    {
+        struct nw_sm_io io = {0};
+
+        io.buf = &f->fbo;
+        io.n = sizeof f->fbo;
+        f->io = io;
+        i->next = get_fbo;
+    }
+
+    return NW_AGAIN;
+}
+
+void nwp_find_function(struct nw_interp *const i, const struct nw_fn *const fn,
+    void (*const next)(struct nw_interp *))
+{
+    const struct nw_i_sm_ffn f = {0};
+    struct nw_i_sm_ffn *const pf = &i->sm.ffn;
+
+    *pf = f;
+    pf->fn = *fn;
+    pf->next = next;
+    i->next = seek_fbo;
+}