From f25b015e5b668028c34974bbb22faa4105c26690 Mon Sep 17 00:00:00 2001
From: Xavier Del Campo Romero <xavi.dcr@tutanota.com>
Date: Sun, 26 Nov 2023 22:43:30 +0100
Subject: First commit

---
 src/op/numeric/CMakeLists.txt | 10 +++++++
 src/op/numeric/i32_sub.c      | 66 +++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 76 insertions(+)
 create mode 100644 src/op/numeric/CMakeLists.txt
 create mode 100644 src/op/numeric/i32_sub.c

(limited to 'src/op/numeric')

diff --git a/src/op/numeric/CMakeLists.txt b/src/op/numeric/CMakeLists.txt
new file mode 100644
index 0000000..a259506
--- /dev/null
+++ b/src/op/numeric/CMakeLists.txt
@@ -0,0 +1,10 @@
+# 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
+    i32_sub.c
+)
diff --git a/src/op/numeric/i32_sub.c b/src/op/numeric/i32_sub.c
new file mode 100644
index 0000000..c3d1352
--- /dev/null
+++ b/src/op/numeric/i32_sub.c
@@ -0,0 +1,66 @@
+/*
+ * 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 <inttypes.h>
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <string.h>
+
+/* Inspired by "INT32-C. Ensure that operations on signed integers do
+ * not result in overflow". */
+static bool signed_overflow(const int32_t a, const int32_t b)
+{
+    return (b > 0 && a < INT32_MIN + b)
+        || (b < 0 && a > INT32_MAX + b);
+}
+
+int op_i32_sub(struct nw_interp *const i)
+{
+    int32_t op1, op2;
+
+    if (interp_stack_pop(i, &op2, sizeof op2))
+    {
+        LOG("%s: interp_stack_pop %s failed\n", __func__, "op2");
+        return -1;
+    }
+    else if (interp_stack_pop(i, &op1, sizeof op1))
+    {
+        LOG("%s: interp_stack_pop %s failed\n", __func__, "op1");
+        return -1;
+    }
+    else if (signed_overflow(op2, op1))
+    {
+        LOG("%s: signed integer overflow (op1=%" PRIi32 ", op2=%" PRIi32 ")\n",
+            __func__, op1, op2);
+        i->exception = "signed integer overflow";
+        return 1;
+    }
+
+    const int32_t result = op2 - op1;
+
+    if (interp_stack_push(i, &result, sizeof result))
+    {
+        LOG("%s: interp_stack_push failed\n", __func__);
+        return -1;
+    }
+
+    return 0;
+}
+
+int check_i32_sub(FILE *const f)
+{
+    return 0;
+}
-- 
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