Bill Fischofer(Bill-Fischofer-Linaro) replied on github web page:
platform/linux-generic/include/odp_chksum_internal.h
line 35
@@ -0,0 +1,59 @@
+/* Copyright (c) 2013, Linaro Limited
+ * All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+/**
+ * @file
+ *
+ * ODP checksum - implementation internal
+ */
+
+#ifndef ODP_CHKSUM_INTERNAL_H_
+#define ODP_CHKSUM_INTERNAL_H_
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/* Simple implementation of ones complement sum.
+ * Based on RFC1071 and its errata.
+ */
+static uint32_t _odp_chksum_ones_comp16_32(const void *p, uint32_t len,
+ odp_bool_t odd_offset)
+
+{
+ uint32_t sum = 0;
+ const uint16_t *data = p;
+
+ if (odd_offset) {
+ uint16_t left_over = 0;
+
+ *(uint8_t *)&left_over = *(const uint8_t *)data;
+ sum = left_over;
+ data++;
Comment:
This erroneously increments `data` by 2 when you want to increment it by 1 here
so that it points to `p + 1`, not `p + 2`. Correct is `data = (const uint16_t
*)((uintptr_t)p + 1);`
> Bill Fischofer(Bill-Fischofer-Linaro) wrote:
> The `odd_offset` parameter is unnecessary here. What matters is whether `p`
> starts on an even or odd byte boundary since that determines whether you can
> fetch `data` as `uint16_t` quantities without making unaligned storage
> references. Each call to `_odp_chksum_ones_comp16_32()` is independent in
> this regard, so it must always be determined anew for each call.
>> Bill Fischofer(Bill-Fischofer-Linaro) wrote:
>> `if (len > 1 && (uintptr_t)p % 2) ...`
>>> Bill Fischofer(Bill-Fischofer-Linaro) wrote:
>>> Drop use of `odd_offset` as noted earlier.
>>>> Bill Fischofer(Bill-Fischofer-Linaro) wrote:
>>>> Checkpatch flag:
>>>> ```
>>>> WARNING: line over 80 characters
>>>> #102: FILE: platform/linux-generic/odp_packet.c:2204:
>>>> + ip_proto = parse_ipv4(prs, &parseptr, &offset, frame_len,
>>>> chksums);
>>>> total: 0 errors, 1 warnings, 0 checks, 163 lines checked
>>>> ```
>>>>> Bill Fischofer(Bill-Fischofer-Linaro) wrote:
>>>>> 2018
https://github.com/Linaro/odp/pull/389#discussion_r161935049
updated_at 2018-01-17 01:41:46
