First commit1st

17 files changed, 1082 insertions, 0 deletions

diff --git a/src/interp/CMakeLists.txt b/src/interp/CMakeLists.txt
new file mode 100644
index 0000000..c3bb726
--- /dev/null
+++ b/src/interp/CMakeLists.txt
@@ -0,0 +1,21 @@
+# 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/.
+
+target_sources(${PROJECT_NAME} PRIVATE
+    global_pop.c
+    globalptr.c
+    initexpr_set.c
+    ops.c
+    run.c
+    stack_pop.c
+    stackptr.c
+    stack_push.c
+    resume.c
+    start.c
+)
+
+add_subdirectory(routines)
diff --git a/src/interp/check_opcode.c b/src/interp/check_opcode.c
new file mode 100644
index 0000000..b10b927
--- /dev/null
+++ b/src/interp/check_opcode.c
@@ -0,0 +1,59 @@
+/*
+ * 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 <nanowasm/nw.h>
+#include <nw/interp.h>
+#include <nw/io.h>
+#include <nw/log.h>
+#include <nw/opcodes.h>
+
+int nwp_interp_check_opcode(const uint8_t op, FILE *const f)
+{
+    static int (*const checks[])(FILE *) =
+    {
+        [OP_UNREACHABLE] = check_unreachable,
+        [OP_NOP] = check_nop,
+        [OP_BLOCK] = check_block,
+        [OP_LOOP] = check_loop,
+        [OP_IF] = check_if,
+        [OP_ELSE] = check_else,
+        [OP_END] = check_end,
+        [OP_BR] = check_br,
+        [OP_BR_IF] = check_br_if,
+        [OP_BR_TABLE] = check_br_table,
+        [OP_RETURN] = check_return,
+        [OP_CALL] = check_call,
+        [OP_CALL_INDIRECT] = check_call_indirect,
+        [OP_GET_LOCAL] = check_get_local,
+        [OP_SET_LOCAL] = check_set_local,
+        [OP_TEE_LOCAL] = check_tee_local,
+        [OP_GET_GLOBAL] = check_get_global,
+        [OP_SET_GLOBAL] = check_set_global,
+        [OP_I32_LOAD] = check_i32_load,
+        [OP_I32_STORE] = check_i32_store,
+        [OP_I32_CONST] = check_i32_const,
+        [OP_I64_CONST] = check_i64_const,
+        [OP_F32_CONST] = check_f32_const,
+        [OP_F64_CONST] = check_f64_const,
+        [OP_I32_SUB] = check_i32_sub
+    };
+
+    if (op >= sizeof checks / sizeof *checks)
+    {
+        LOG("%s: invalid opcode %#" PRIx8 "\n", __func__, op);
+        return 1;
+    }
+    else if (!checks[op])
+    {
+        LOG("%s: unsupported opcode %#" PRIx8 "\n", __func__, op);
+        return 1;
+    }
+
+    return checks[op](f);
+}
diff --git a/src/interp/global_pop.c b/src/interp/global_pop.c
new file mode 100644
index 0000000..4066d63
--- /dev/null
+++ b/src/interp/global_pop.c
@@ -0,0 +1,34 @@
+/*
+ * 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 <nanowasm/nw.h>
+#include <nw/interp.h>
+#include <nw/log.h>
+#include <nw/types.h>
+#include <stddef.h>
+#include <string.h>
+
+int interp_global_pop(struct nw_interp *const i, void *const dst,
+    const size_t n)
+{
+    const void *const src = (const char *)i->cfg.global.buf + i->global_i;
+
+    if (i->global_i < n)
+    {
+        static const char exc[] = "global memory underflow";
+
+        LOG("%s: %s\n", __func__, exc);
+        i->exception = exc;
+        return -1;
+    }
+
+    i->global_i -= n;
+    memcpy(dst, src, n);
+    return 0;
+}
diff --git a/src/interp/globalptr.c b/src/interp/globalptr.c
new file mode 100644
index 0000000..486f5ba
--- /dev/null
+++ b/src/interp/globalptr.c
@@ -0,0 +1,17 @@
+/*
+ * 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 <nanowasm/nw.h>
+#include <nw/interp.h>
+#include <nw/types.h>
+
+void *interp_globalptr(const struct nw_interp *const i)
+{
+    return (char *)i->cfg.global.buf + i->global_i;
+}
diff --git a/src/interp/initexpr_set.c b/src/interp/initexpr_set.c
new file mode 100644
index 0000000..57601be
--- /dev/null
+++ b/src/interp/initexpr_set.c
@@ -0,0 +1,28 @@
+/*
+ * 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 <nanowasm/nw.h>
+#include <nw/interp.h>
+#include <nw/opcodes.h>
+
+static const enum opcode opcodes[] =
+{
+    OP_NOP,
+    OP_END,
+    OP_I32_CONST,
+    OP_I64_CONST,
+    OP_F32_CONST,
+    OP_F64_CONST
+};
+
+const struct nwp_interp_set nwp_interp_initexpr_set =
+{
+    .opcodes = opcodes,
+    .n = sizeof opcodes / sizeof *opcodes
+};
diff --git a/src/interp/interp.c b/src/interp/interp.c
new file mode 100644
index 0000000..dbeb126
--- /dev/null
+++ b/src/interp/interp.c
@@ -0,0 +1,411 @@
+/*
+ * 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 <nanowasm/nw.h>
+#include <nw/log.h>
+#include <nw/interp.h>
+#include <nw/opcodes.h>
+#include <nw/ops.h>
+#include <nw/sections.h>
+#include <nw/types.h>
+#include <errno.h>
+#include <limits.h>
+#include <inttypes.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+static const enum opcode initexpr_opcodes[] =
+{
+    OP_NOP,
+    OP_END,
+    OP_I32_CONST,
+    OP_I64_CONST,
+    OP_F32_CONST,
+    OP_F64_CONST
+};
+
+const struct interp_set nwp_interp_initexpr_set =
+{
+    .opcodes = initexpr_opcodes,
+    .n = sizeof initexpr_opcodes / sizeof *initexpr_opcodes
+};
+
+static int (*const ops[])(struct nw_interp *) =
+{
+    [OP_UNREACHABLE] = op_unreachable,
+    [OP_NOP] = op_nop,
+    [OP_BLOCK] = op_block,
+    [OP_LOOP] = op_loop,
+    [OP_IF] = op_if,
+    [OP_ELSE] = op_else,
+    [OP_END] = op_end,
+    [OP_BR] = op_br,
+    [OP_BR_IF] = op_br_if,
+    [OP_BR_TABLE] = op_br_table,
+    [OP_RETURN] = op_return,
+    [OP_CALL] = op_call,
+    [OP_CALL_INDIRECT] = op_call_indirect,
+    [OP_GET_LOCAL] = op_get_local,
+    [OP_SET_LOCAL] = op_set_local,
+    [OP_TEE_LOCAL] = op_tee_local,
+    [OP_GET_GLOBAL] = op_get_global,
+    [OP_SET_GLOBAL] = op_set_global,
+    [OP_I32_LOAD] = op_i32_load,
+    [OP_I32_STORE] = op_i32_store,
+    [OP_I32_CONST] = op_i32_const,
+    [OP_I64_CONST] = op_i64_const,
+    [OP_F32_CONST] = op_f32_const,
+    [OP_F64_CONST] = op_f64_const,
+    [OP_I32_SUB] = op_i32_sub
+};
+
+int interp_run(struct nw_interp *const i)
+{
+    uint8_t op;
+
+    if (!fread(&op, sizeof op, 1, i->f))
+    {
+        LOG("%s: fread(3) failed, feof=%d, ferror=%d\n", __func__, feof(i->f),
+            ferror(i->f));
+        i->exception = "I/O error";
+        return -1;
+    }
+    else if (op >= sizeof ops / sizeof *ops)
+    {
+        LOG("%s: invalid opcode %#" PRIx8 "\n", __func__, op);
+        i->exception = "invalid opcode";
+        return -1;
+    }
+    else if (!ops[op])
+    {
+        LOG("%s: unsupported opcode %#" PRIx8 "\n", __func__, op);
+        i->exception = "invalid opcode";
+        return -1;
+    }
+
+    return ops[op](i);
+}
+
+static int run_opcode_limited(struct nw_interp *const in,
+    const struct interp_set *const set)
+{
+    uint8_t op;
+
+    if (!fread(&op, sizeof op, 1, in->f))
+    {
+        LOG("%s: fread(3) failed, feof=%d, ferror=%d\n",
+            __func__, feof(in->f), ferror(in->f));
+        in->exception = "I/O error";
+        return -1;
+    }
+
+    for (size_t i = 0; i < set->n; i++)
+        if (op == set->opcodes[i])
+            return ops[op](in);
+
+    LOG("%s: unexpected opcode %#" PRIx8 "\n", __func__, op);
+    in->exception = "invalid opcode";
+    return -1;
+}
+
+int interp_run_limited(struct nw_interp *const i,
+    const struct interp_set *const set)
+{
+    while (!i->exit)
+        if (run_opcode_limited(i, set))
+        {
+            LOG("%s: run_opcode_limited failed\n", __func__);
+            return -1;
+        }
+
+    return 0;
+}
+
+int interp_check_opcode(const uint8_t op, FILE *const f)
+{
+    static int (*const checks[])(FILE *) =
+    {
+        [OP_UNREACHABLE] = check_unreachable,
+        [OP_NOP] = check_nop,
+        [OP_BLOCK] = check_block,
+        [OP_LOOP] = check_loop,
+        [OP_IF] = check_if,
+        [OP_ELSE] = check_else,
+        [OP_END] = check_end,
+        [OP_BR] = check_br,
+        [OP_BR_IF] = check_br_if,
+        [OP_BR_TABLE] = check_br_table,
+        [OP_RETURN] = check_return,
+        [OP_CALL] = check_call,
+        [OP_CALL_INDIRECT] = check_call_indirect,
+        [OP_GET_LOCAL] = check_get_local,
+        [OP_SET_LOCAL] = check_set_local,
+        [OP_TEE_LOCAL] = check_tee_local,
+        [OP_GET_GLOBAL] = check_get_global,
+        [OP_SET_GLOBAL] = check_set_global,
+        [OP_I32_LOAD] = check_i32_load,
+        [OP_I32_STORE] = check_i32_store,
+        [OP_I32_CONST] = check_i32_const,
+        [OP_I64_CONST] = check_i64_const,
+        [OP_F32_CONST] = check_f32_const,
+        [OP_F64_CONST] = check_f64_const,
+        [OP_I32_SUB] = check_i32_sub
+    };
+
+    if (op >= sizeof checks / sizeof *checks)
+    {
+        LOG("%s: invalid opcode %#" PRIx8 "\n", __func__, op);
+        return 1;
+    }
+    else if (!checks[op])
+    {
+        LOG("%s: unsupported opcode %#" PRIx8 "\n", __func__, op);
+        return 1;
+    }
+
+    return checks[op](f);
+}
+
+int interp_start(const struct nw_interp_cfg *const cfg, FILE *const f,
+    struct nw_interp *const i)
+{
+    *i = (const struct nw_interp)
+    {
+        .f = f,
+        .cfg = *cfg
+    };
+
+    return 0;
+}
+
+void *nwp_interp_stackptr(const struct nw_interp *const i)
+{
+    return (char *)i->cfg.stack.buf + i->stack_i;
+}
+
+struct retval_priv
+{
+    enum value_type type;
+
+    union
+    {
+        int32_t i32;
+        int64_t i64;
+        float f32;
+        double f64;
+    } u;
+};
+
+static int get_i32(struct nw_interp *const i, struct retval_priv *const rp)
+{
+    return interp_stack_pop(i, &rp->u.i32, sizeof rp->u.i32);
+}
+
+static int get_i64(struct nw_interp *const i, struct retval_priv *const rp)
+{
+    return interp_stack_pop(i, &rp->u.i64, sizeof rp->u.i64);
+}
+
+static int get_f32(struct nw_interp *const i, struct retval_priv *const rp)
+{
+    return interp_stack_pop(i, &rp->u.f32, sizeof rp->u.f32);
+}
+
+static int get_f64(struct nw_interp *const i, struct retval_priv *const rp)
+{
+    return interp_stack_pop(i, &rp->u.f64, sizeof rp->u.f64);
+}
+
+static int get_retval(struct nw_interp *const i, struct retval_priv *const rp)
+{
+    const struct retval *const r = &i->fp->retval;
+    const enum value_type v = r->type;
+    static int (*const f[])(struct nw_interp *, struct retval_priv *) =
+    {
+        [VALUE_TYPE_I32] = get_i32,
+        [VALUE_TYPE_I64] = get_i64,
+        [VALUE_TYPE_F32] = get_f32,
+        [VALUE_TYPE_F64] = get_f64
+    };
+
+    if (f[r->type](i, rp))
+    {
+        LOG("%s: callback for type %s failed\n", __func__,
+            value_type_tostr(v));
+        return -1;
+    }
+
+    rp->type = r->type;
+    return 0;
+}
+
+int interp_pop(struct nw_interp *const i)
+{
+    if (!i->fp)
+    {
+        static const char exc[] = "no frame pointer";
+
+        LOG("%s: %s\n", __func__, exc);
+        i->exception = exc;
+        return -1;
+    }
+
+    const struct retval *const r = &i->fp->retval;
+    struct retval_priv rp;
+
+    if (r->returns && get_retval(i, &rp))
+    {
+        LOG("%s: get_retval failed\n", __func__);
+        return -1;
+    }
+
+#if 0
+#error TODO: do Wasm modules really have an exit status?
+#endif
+
+    if (!(i->fp = i->fp->prev))
+    {
+        /* Entry point is always assumed to return int, which is
+         * defined as an i32 variable according to Wasm. */
+        if (rp.type != VALUE_TYPE_I32)
+        {
+            LOG("%s: expected i32 return type, got %s\n", __func__,
+                value_type_tostr(rp.type));
+            i->exception = "unexpected return type";
+            return -1;
+        }
+
+        i->retval = rp.u.i32;
+        i->exit = true;
+    }
+
+    return 0;
+}
+
+int interp_stack_push(struct nw_interp *const i, const void *const src,
+    const size_t n)
+{
+    const size_t max = i->cfg.stack.n;
+    void *const dst = nwp_interp_stackptr(i);
+
+    if (max < n || i->stack_i > max - n)
+    {
+        static const char exc[] = "stack overflow";
+
+        LOG("%s: %s\n", __func__, exc);
+        i->exception = exc;
+        return -1;
+    }
+
+    memcpy(dst, src, n);
+    i->stack_i += n;
+    return 0;
+}
+
+int interp_stack_pop(struct nw_interp *const i, void *const dst,
+    const size_t n)
+{
+    if (i->stack_i < n)
+    {
+        static const char exc[] = "stack underflow";
+
+        LOG("%s: %s\n", __func__, exc);
+        i->exception = exc;
+        return -1;
+    }
+
+    i->stack_i -= n;
+    memcpy(dst, nwp_interp_stackptr(i), n);
+    return 0;
+}
+
+int interp_heap_store(struct nw_interp *const i, const size_t addr,
+    const void *const src, const size_t n)
+{
+    if (i->cfg.heap.n < n || addr > i->cfg.heap.n - n)
+    {
+        static const char exc[] = "heap overflow";
+
+        LOG("%s: %s\n", __func__, exc);
+        i->exception = exc;
+        return -1;
+    }
+
+    void *const dst = (char *)i->cfg.heap.buf + addr;
+
+    memcpy(dst, src, n);
+    return 0;
+}
+
+int interp_heap_load(struct nw_interp *const i, const size_t addr,
+    void *const dst, const size_t n)
+{
+    const size_t max = i->cfg.heap.n;
+
+    if (max < n || addr > max - n)
+    {
+        static const char exc[] = "heap out-of-bounds access";
+
+        LOG("%s: %s (%lu, max %zu)\n", __func__, exc, (unsigned long)addr, max);
+        i->exception = exc;
+        return -1;
+    }
+
+    const void *const src = (const char *)i->cfg.heap.buf + addr;
+
+    memcpy(dst, src, n);
+    return 0;
+}
+
+int interp_global_push(struct nw_interp *const i, const void *const src,
+    const size_t n)
+{
+    const size_t max = i->cfg.global.n;
+    void *const dst = (char *)i->cfg.global.buf + i->global_i;
+
+    if (max < n || i->global_i > max - n)
+    {
+        static const char exc[] = "global memory overflow";
+
+        LOG("%s: %s\n", __func__, exc);
+        i->exception = exc;
+        return -1;
+    }
+
+    memcpy(dst, src, n);
+    i->global_i += n;
+    return 0;
+}
+
+int interp_global_pop(struct nw_interp *const i, void *const dst,
+    const size_t n)
+{
+    const void *const src = (const char *)i->cfg.global.buf + i->global_i;
+
+    if (i->global_i < n)
+    {
+        static const char exc[] = "global memory underflow";
+
+        LOG("%s: %s\n", __func__, exc);
+        i->exception = exc;
+        return -1;
+    }
+
+    i->global_i -= n;
+    memcpy(dst, src, n);
+    return 0;
+}
+
+void *interp_globalptr(const struct nw_interp *const i)
+{
+    return (char *)i->cfg.global.buf + i->global_i;
+}
diff --git a/src/interp/ops.c b/src/interp/ops.c
new file mode 100644
index 0000000..ea7c2b9
--- /dev/null
+++ b/src/interp/ops.c
@@ -0,0 +1,53 @@
+/*
+ * 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 <nanowasm/nw.h>
+#include <nw/opcodes.h>
+#include <nw/ops.h>
+#include <nw/interp.h>
+
+static void (*const ops[])(struct nw_interp *) =
+{
+    [OP_UNREACHABLE] = nwp_op_unreachable,
+    [OP_NOP] = nwp_op_nop,
+    [OP_I32_LOAD] = nwp_op_i32_load,
+    [OP_I32_CONST] = nwp_op_i32_const,
+    [OP_END] = nwp_op_end,
+#if 0
+    [OP_BLOCK] = nwp_op_block,
+    [OP_LOOP] = nwp_op_loop,
+    [OP_IF] = nwp_op_if,
+    [OP_ELSE] = nwp_op_else,
+
+    [OP_BR] = nwp_op_br,
+    [OP_BR_IF] = nwp_op_br_if,
+    [OP_BR_TABLE] = nwp_op_br_table,
+    [OP_RETURN] = nwp_op_return,
+    [OP_CALL] = nwp_op_call,
+    [OP_CALL_INDIRECT] = nwp_op_call_indirect,
+    [OP_GET_LOCAL] = nwp_op_get_local,
+    [OP_SET_LOCAL] = nwp_op_set_local,
+    [OP_TEE_LOCAL] = nwp_op_tee_local,
+    [OP_GET_GLOBAL] = nwp_op_get_global,
+    [OP_SET_GLOBAL] = nwp_op_set_global,
+
+    [OP_I32_STORE] = nwp_op_i32_store,
+
+    [OP_I64_CONST] = nwp_op_i64_const,
+    [OP_F32_CONST] = nwp_op_f32_const,
+    [OP_F64_CONST] = nwp_op_f64_const,
+    [OP_I32_SUB] = nwp_op_i32_sub
+#endif
+};
+
+const struct nwp_ops nwp_ops =
+{
+    .ops = ops,
+    .n = sizeof ops / sizeof *ops
+};
diff --git a/src/interp/resume.c b/src/interp/resume.c
new file mode 100644
index 0000000..e808889
--- /dev/null
+++ b/src/interp/resume.c
@@ -0,0 +1,20 @@
+/*
+ * 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 <nanowasm/nw.h>
+#include <nanowasm/types.h>
+#include <nw/interp.h>
+
+void nwp_interp_resume(struct nw_interp *const i)
+{
+    if (i->set)
+        nwp_interp_limited(i);
+    else
+        nwp_interp_full(i);
+}
diff --git a/src/interp/routines/CMakeLists.txt b/src/interp/routines/CMakeLists.txt
new file mode 100644
index 0000000..eb76ed3
--- /dev/null
+++ b/src/interp/routines/CMakeLists.txt
@@ -0,0 +1,12 @@
+# 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/.
+
+target_sources(${PROJECT_NAME} PRIVATE
+    find_export.c
+    full.c
+    limited.c
+)
diff --git a/src/interp/routines/find_export.c b/src/interp/routines/find_export.c
new file mode 100644
index 0000000..f82e5f9
--- /dev/null
+++ b/src/interp/routines/find_export.c
@@ -0,0 +1,202 @@
+/*
+ * 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 <nanowasm/nw.h>
+#include <nanowasm/types.h>
+#include <nw/interp.h>
+#include <nw/io.h>
+#include <nw/log.h>
+#include <nw/routines.h>
+#include <inttypes.h>
+#include <string.h>
+
+static enum nw_state entry_loop(struct nw_interp *i);
+
+static enum nw_state get_index(struct nw_interp *const i)
+{
+    const struct nw_io_cfg *const cfg = &i->cfg.io;
+    struct nw_i_sm_exp *const e = &i->sm.export;
+    struct nw_sm_leb128 *const l = &e->leb128;
+    const enum nw_state n = nwp_varuint32(cfg, l, &e->index);
+
+    if (n)
+        return n;
+
+    i->next = e->next;
+    return NW_AGAIN;
+}
+
+static enum nw_state get_kind(struct nw_interp *const i)
+{
+    uint8_t kind;
+    const struct nw_io_cfg *const cfg = &i->cfg.io;
+    struct nw_sm_io io = {.buf = &kind, .n = sizeof kind};
+    const enum nw_state n = nwp_io_read(cfg, &io);
+
+    if (n)
+        return n;
+    else if (kind >= NW_KINDS)
+    {
+        static const char exc[] = "invalid export kind";
+
+        i->exception = exc;
+        LOG("%s: %s: %" PRIu8 "\n", __func__, exc, kind);
+        return NW_FATAL;
+    }
+
+    struct nw_i_sm_exp *const e = &i->sm.export;
+
+    e->kind = kind;
+    i->next = get_index;
+    return NW_AGAIN;
+}
+
+static enum nw_state skip_index(struct nw_interp *const i)
+{
+    const struct nw_io_cfg *const cfg = &i->cfg.io;
+    struct nw_i_sm_exp *const e = &i->sm.export;
+    struct nw_sm_leb128 *const l = &e->leb128;
+    const enum nw_state n = nwp_varuint32(cfg, l, &(nw_varuint32){0});
+
+    if (n)
+        return n;
+
+    e->entry_i++;
+    i->next = entry_loop;
+    return NW_AGAIN;
+}
+
+static enum nw_state skip_kind(struct nw_interp *const i)
+{
+    const struct nw_io_cfg *const cfg = &i->cfg.io;
+    struct nw_sm_io io = {.buf = &(uint8_t){0}, .n = sizeof (uint8_t)};
+    const enum nw_state n = nwp_io_read(cfg, &io);
+
+    if (n)
+        return n;
+
+    i->next = skip_index;
+    return NW_AGAIN;
+}
+
+static enum nw_state skip_field_str(struct nw_interp *const i)
+{
+    const struct nw_io_cfg *const cfg = &i->cfg.io;
+    const struct nw_i_sm_exp *const e = &i->sm.export;
+    const long offset = e->len - e->len_i;
+    const enum nw_state n = cfg->seek(offset, NW_SEEK_CUR, cfg->user);
+
+    if (n)
+        return n;
+
+    i->next = skip_kind;
+    return NW_AGAIN;
+}
+
+static enum nw_state compare(struct nw_interp *const i)
+{
+    uint8_t byte;
+    const struct nw_io_cfg *const cfg = &i->cfg.io;
+    struct nw_i_sm_exp *const e = &i->sm.export;
+    struct nw_sm_io io = {.buf = &byte, .n = sizeof byte};
+    const enum nw_state n = nwp_io_read(cfg, &io);
+
+    if (n)
+        return n;
+    else if (byte != e->sym[e->len_i++])
+        i->next = skip_field_str;
+    else if (e->len_i >= e->len)
+        i->next = get_kind;
+
+    return NW_AGAIN;
+}
+
+static enum nw_state get_len(struct nw_interp *const i)
+{
+    const struct nw_io_cfg *const cfg = &i->cfg.io;
+    struct nw_i_sm_exp *const e = &i->sm.export;
+    struct nw_sm_leb128 *const l = &e->leb128;
+    const enum nw_state n = nwp_varuint32(cfg, l, &e->len);
+
+    if (n)
+        return n;
+    else if (e->len != strlen(e->sym))
+        i->next = skip_field_str;
+    else
+        i->next = compare;
+
+    return NW_AGAIN;
+}
+
+static enum nw_state entry_loop(struct nw_interp *const i)
+{
+    struct nw_i_sm_exp *const e = &i->sm.export;
+
+    if (e->entry_i >= e->count)
+    {
+        static const char exc[] = "failed to find symbol";
+
+        i->exception = exc;
+        LOG("%s: %s: %s\n", __func__, exc, e->sym);
+        return NW_FATAL;
+    }
+
+    e->len_i = 0;
+    i->next = get_len;
+    return NW_AGAIN;
+}
+
+static enum nw_state get_count(struct nw_interp *const i)
+{
+    const struct nw_io_cfg *const cfg = &i->cfg.io;
+    struct nw_i_sm_exp *const e = &i->sm.export;
+    struct nw_sm_leb128 *const l = &e->leb128;
+    const enum nw_state n = nwp_varuint32(cfg, l, &e->count);
+
+    if (n)
+        return n;
+
+    i->next = entry_loop;
+    return NW_AGAIN;
+}
+
+static enum nw_state seek(struct nw_interp *const i)
+{
+    const struct nw_mod *const m = i->cfg.m;
+    const struct nw_io_cfg *const cfg = &i->cfg.io;
+
+    if (!m->sections[NW_SECTION_EXPORT])
+    {
+        static const char exc[] = "section not found";
+
+        i->exception = exc;
+        LOG("%s: %s: %s\n", __func__, exc, "export");
+        return NW_FATAL;
+    }
+
+    const enum nw_state n = cfg->seek(m->sections[NW_SECTION_EXPORT],
+        NW_SEEK_SET, cfg->user);
+
+    if (n)
+        return n;
+
+    i->next = get_count;
+    return NW_AGAIN;
+}
+
+void nwp_find_export(struct nw_interp *i, const char *sym,
+    enum nw_state (*const next)(struct nw_interp *))
+{
+    i->next = seek;
+    i->sm.export = (const struct nw_i_sm_exp)
+    {
+        .sym = sym,
+        .next = next
+    };
+}
diff --git a/src/interp/routines/full.c b/src/interp/routines/full.c
new file mode 100644
index 0000000..c60432d
--- /dev/null
+++ b/src/interp/routines/full.c
@@ -0,0 +1,48 @@
+/*
+ * 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/interp.h>
+#include <nw/io.h>
+#include <nw/log.h>
+#include <nw/opcodes.h>
+#include <nw/ops.h>
+#include <nw/routines.h>
+#include <inttypes.h>
+
+static enum nw_state get_bytecode(struct nw_interp *const i)
+{
+    const struct nw_io_cfg *const cfg = &i->cfg.io;
+    struct nw_i_sm_b *const b = &i->sm.bytecode;
+    const enum nw_state n = nwp_io_read(cfg, &b->io);
+
+    if (n)
+        return n;
+    else if (b->op >= nwp_ops.n)
+    {
+        static const char exc[] = "invalid opcode";
+
+        LOG("%s: %s: %#" PRIx8 "\n", __func__, exc, b->op);
+        i->exception = exc;
+    }
+
+    nwp_ops.ops[b->op](i);
+    return NW_AGAIN;
+}
+
+void nwp_interp_full(struct nw_interp *const i)
+{
+    struct nw_i_sm_b *const b = &i->sm.bytecode;
+
+    i->next = get_bytecode;
+    b->io = (const struct nw_sm_io)
+    {
+        .buf = &b->op,
+        .n = sizeof b->op
+    };
+}
diff --git a/src/interp/routines/limited.c b/src/interp/routines/limited.c
new file mode 100644
index 0000000..766b2d3
--- /dev/null
+++ b/src/interp/routines/limited.c
@@ -0,0 +1,54 @@
+/*
+ * 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 <nanowasm/nw.h>
+#include <nanowasm/types.h>
+#include <nw/interp.h>
+#include <nw/io.h>
+#include <nw/log.h>
+#include <nw/routines.h>
+#include <stddef.h>
+#include <inttypes.h>
+
+static enum nw_state get_bytecode(struct nw_interp *const in)
+{
+    const struct nw_io_cfg *const cfg = &in->cfg.io;
+    struct nw_i_sm_b *const b = &in->sm.bytecode;
+    const enum nw_state n = nwp_io_read(cfg, &b->io);
+
+    if (n)
+        return n;
+
+    const struct nwp_interp_set *const set = in->set;
+
+    for (size_t i = 0; i < set->n; i++)
+        if (b->op == set->opcodes[i])
+        {
+            nwp_ops.ops[b->op](in);
+            return NW_AGAIN;
+        }
+
+    static const char exc[] = "invalid opcode";
+
+    LOG("%s: %s: %#" PRIx8 "\n", __func__, exc, b->op);
+    in->exception = exc;
+    return NW_FATAL;
+}
+
+void nwp_interp_limited(struct nw_interp *const i)
+{
+    struct nw_i_sm_b *const b = &i->sm.bytecode;
+
+    i->next = get_bytecode;
+    b->io = (const struct nw_sm_io)
+    {
+        .buf = &b->op,
+        .n = sizeof b->op
+    };
+}
diff --git a/src/interp/run.c b/src/interp/run.c
new file mode 100644
index 0000000..ef7f614
--- /dev/null
+++ b/src/interp/run.c
@@ -0,0 +1,16 @@
+/*
+ * 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 <nanowasm/nw.h>
+#include <nw/interp.h>
+
+enum nw_state nwp_interp_run(struct nw_interp *const i)
+{
+    return i->next(i);
+}
diff --git a/src/interp/stack_pop.c b/src/interp/stack_pop.c
new file mode 100644
index 0000000..8650be1
--- /dev/null
+++ b/src/interp/stack_pop.c
@@ -0,0 +1,31 @@
+/*
+ * 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 <nanowasm/nw.h>
+#include <nw/interp.h>
+#include <nw/log.h>
+#include <stddef.h>
+#include <string.h>
+
+int interp_stack_pop(struct nw_interp *const i, void *const dst,
+    const size_t n)
+{
+    if (i->stack_i < n)
+    {
+        static const char exc[] = "stack underflow";
+
+        LOG("%s: %s\n", __func__, exc);
+        i->exception = exc;
+        return -1;
+    }
+
+    i->stack_i -= n;
+    memcpy(dst, nwp_interp_stackptr(i), n);
+    return 0;
+}
diff --git a/src/interp/stack_push.c b/src/interp/stack_push.c
new file mode 100644
index 0000000..2145423
--- /dev/null
+++ b/src/interp/stack_push.c
@@ -0,0 +1,34 @@
+/*
+ * 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 <nanowasm/nw.h>
+#include <nw/interp.h>
+#include <nw/log.h>
+#include <stddef.h>
+#include <string.h>
+
+int nwp_interp_stack_push(struct nw_interp *const i, const void *const src,
+    const size_t n)
+{
+    const size_t max = i->cfg.stack.n;
+    void *const dst = nwp_interp_stackptr(i);
+
+    if (max < n || i->stack_i > max - n)
+    {
+        static const char exc[] = "stack overflow";
+
+        LOG("%s: %s\n", __func__, exc);
+        i->exception = exc;
+        return -1;
+    }
+
+    memcpy(dst, src, n);
+    i->stack_i += n;
+    return 0;
+}
diff --git a/src/interp/stackptr.c b/src/interp/stackptr.c
new file mode 100644
index 0000000..6b95e1d
--- /dev/null
+++ b/src/interp/stackptr.c
@@ -0,0 +1,16 @@
+/*
+ * 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 <nanowasm/nw.h>
+#include <nw/interp.h>
+
+void *nwp_interp_stackptr(const struct nw_interp *const i)
+{
+    return (char *)i->cfg.stack.buf + i->stack_i;
+}
diff --git a/src/interp/start.c b/src/interp/start.c
new file mode 100644
index 0000000..9d98ccb
--- /dev/null
+++ b/src/interp/start.c
@@ -0,0 +1,26 @@
+/*
+ * 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 <nanowasm/nw.h>
+#include <nanowasm/types.h>
+#include <nw/interp.h>
+
+int nwp_interp_start(const struct nw_interp_cfg *const cfg,
+    const struct nwp_interp_set *const set,
+    struct nw_interp *const i)
+{
+    *i = (const struct nw_interp)
+    {
+        .cfg = *cfg,
+        .set = set
+    };
+
+    nwp_interp_resume(i);
+    return 0;
+}