raiden00pl commented on code in PR #1460: URL: https://github.com/apache/nuttx-apps/pull/1460#discussion_r1051649667
########## logging/nxscope/nxscope_pser.c: ########## @@ -0,0 +1,297 @@ +/**************************************************************************** + * apps/logging/nxscope/nxscope_pser.c + * + * Licensed to the Apache Software Foundation (ASF) under one or more + * contributor license agreements. See the NOTICE file distributed with + * this work for additional information regarding copyright ownership. The + * ASF licenses this file to you under the Apache License, Version 2.0 (the + * "License"); you may not use this file except in compliance with the + * License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT + * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the + * License for the specific language governing permissions and limitations + * under the License. + * + ****************************************************************************/ + +/**************************************************************************** + * Included Files + ****************************************************************************/ + +#include <nuttx/config.h> + +#include <assert.h> +#include <debug.h> +#include <byteswap.h> +#include <errno.h> +#include <string.h> + +#include <nuttx/crc16.h> + +#include <logging/nxscope/nxscope.h> + +/**************************************************************************** + * Pre-processor Definitions + ****************************************************************************/ + +#define NXSCOPE_HDR_LEN (sizeof(struct nxscope_hdr_s)) +#define NXSCOPE_DATA_START (NXSCOPE_HDR_LEN) +#define NXSCOPE_BASEFRAME_LEN (NXSCOPE_HDR_LEN + NXSCOPE_CRC_LEN) +#define NXSCOPE_HDR_SOF (0x55) +#define NXSCOPE_CRC_LEN (sizeof(uint16_t)) + +/**************************************************************************** + * Private Type Definition + ****************************************************************************/ + +/* Nxscope serial protocol frame: + * +--------------------+------------+-------------+ + * | HDR [4B] | frame data | footer [2B] | + * +-----+---------+----+------------+-------------+ + * | SOF | len [1] | id | frame data | crc16 [2] | + * +-----+----+----+----+------------+------+------+ + * | 0 | 1 | 2 | 3 | ... | n+1 | n+2 | + * +-----+----+----+----+------------+------+------+ + * + * [1] - always little-endian + * [2] - always big-endian + */ + +/* Nxscope header */ + +begin_packed_struct struct nxscope_hdr_s +{ + uint8_t sof; /* SOF */ + uint16_t len; /* Frame length */ + uint8_t id; /* Frame ID */ +} end_packed_struct; + +/* Nxscope footer */ + +begin_packed_struct struct nxscope_footer_s +{ + uint16_t crc16; /* check sum (see nxscope_frame_final()) */ +} end_packed_struct; + +/**************************************************************************** + * Private Function Protototypes + ****************************************************************************/ + +static int nxscope_frame_get(FAR struct nxscope_proto_s *p, + FAR uint8_t *buff, size_t len, + FAR struct nxscope_frame_s *frame); +static int nxscope_frame_final(FAR struct nxscope_proto_s *p, + uint8_t id, + FAR uint8_t *buff, FAR size_t *len); + +/**************************************************************************** + * Public Data + ****************************************************************************/ + +struct nxscope_proto_ops_s g_nxscope_proto_ser_ops = +{ + .frame_get = nxscope_frame_get, + .frame_final = nxscope_frame_final, +}; + +struct nxscope_proto_s g_nxscope_proto_ser = +{ + .priv = NULL, + .ops = &g_nxscope_proto_ser_ops, + .footlen = NXSCOPE_CRC_LEN, + .hdrlen = NXSCOPE_HDR_LEN +}; + +/**************************************************************************** + * Private Functions + ****************************************************************************/ + +/**************************************************************************** + * Name: nxscope_hdr_fill + ****************************************************************************/ + +static void nxscope_hdr_fill(FAR uint8_t *buff, uint8_t id, uint16_t len) +{ + FAR struct nxscope_hdr_s *hdr = NULL; + + hdr = (FAR struct nxscope_hdr_s *) buff; + + hdr->sof = NXSCOPE_HDR_SOF; + + /* Length always as little endian */ + +#ifdef CONFIG_ENDIAN_BIG + hdr->len = bswap_16(len); +#else + hdr->len = len; +#endif + + hdr->id = id; +} + +/**************************************************************************** + * Name: nxscope_frame_get + ****************************************************************************/ + +static int nxscope_frame_get(FAR struct nxscope_proto_s *p, + FAR uint8_t *buff, size_t len, + FAR struct nxscope_frame_s *frame) +{ + FAR struct nxscope_hdr_s *hdr = NULL; + uint16_t crc = 0; + int ret = OK; + int i = 0; + + DEBUGASSERT(p); + DEBUGASSERT(buff); + DEBUGASSERT(frame); + + UNUSED(p); + + /* Find SOF */ + + for (i = 0 ; i < len - NXSCOPE_HDR_LEN; i += 1) + { + hdr = (FAR struct nxscope_hdr_s *) &buff[i]; + + /* Verify SOF */ + + if (hdr->sof == NXSCOPE_HDR_SOF) + { + break; + } + } + + if (hdr->sof != NXSCOPE_HDR_SOF) + { + ret = -EINVAL; + goto errout; + } + + /* Verify len - always little-endian */ + +#ifdef CONFIG_ENDIAN_BIG + hdr->len = bswap_16(hdr->len); +#endif + + if ((len - i) < hdr->len) + { + ret = -EINVAL; + goto errout; + } + + /* Verify crc16 for the whole frame */ + + crc = crc16(&buff[i], hdr->len); + if (crc != 0) + { + _err("ERROR: invalid crc16 %d\n", crc); + ret = -EINVAL; + goto errout; + } + + /* Return the frame data */ + + frame->id = hdr->id; + frame->data = &buff[i + NXSCOPE_DATA_START]; + frame->drop = hdr->len + i; + frame->dlen = hdr->len - NXSCOPE_BASEFRAME_LEN; + +errout: + return ret; +} + +/**************************************************************************** + * Name: nxscope_frame_final + ****************************************************************************/ + +static int nxscope_frame_final(FAR struct nxscope_proto_s *p, + uint8_t id, + FAR uint8_t *buff, FAR size_t *len) +{ + uint16_t crc = 0; + int ret = OK; + + DEBUGASSERT(p); + DEBUGASSERT(buff); + DEBUGASSERT(len); + + if (*len <= NXSCOPE_HDR_LEN) + { + /* No data */ + + ret = -ENODATA; + goto errout; Review Comment: I prefer one `return` statement when possible -- This is an automated message from the Apache Git Service. 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