mirror of https://github.com/ArduPilot/ardupilot
72 lines
2.2 KiB
C++
72 lines
2.2 KiB
C++
/*
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#pragma once
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#include "AP_Filesystem_backend.h"
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#include <AP_Param/AP_Param.h>
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class AP_Filesystem_Param : public AP_Filesystem_Backend
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{
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public:
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// functions that closely match the equivalent posix calls
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int open(const char *fname, int flags) override;
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int close(int fd) override;
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int32_t read(int fd, void *buf, uint32_t count) override;
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int32_t lseek(int fd, int32_t offset, int whence) override;
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int stat(const char *pathname, struct stat *stbuf) override;
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private:
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// we maintain two cursors per open file to minimise seeking
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// when filling in gaps
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static constexpr uint8_t num_cursors = 2;
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// only allow up to 4 files at a time
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static constexpr uint8_t max_open_file = 4;
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// maximum size of one packed parameter
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static constexpr uint8_t max_pack_len = AP_MAX_NAME_SIZE + 2 + 4 + 3;
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// header at front of the file
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struct header {
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uint16_t magic = 0x671b;
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uint16_t num_params;
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uint16_t total_params;
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};
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struct cursor {
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AP_Param::ParamToken token;
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uint32_t token_ofs;
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char last_name[AP_MAX_NAME_SIZE+1];
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uint8_t trailer_len;
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uint8_t trailer[max_pack_len];
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uint16_t idx;
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};
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struct rfile {
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bool open;
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uint16_t read_size;
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uint16_t start;
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uint16_t count;
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uint32_t file_ofs;
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struct cursor *cursors;
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} file[max_open_file];
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bool token_seek(const struct rfile &r, const uint32_t data_ofs, struct cursor &c);
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uint8_t pack_param(const struct rfile &r, struct cursor &c, uint8_t *buf);
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bool check_file_name(const char *fname);
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};
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