1 /* 2 * Copyright (C) 2015 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 #include <inttypes.h> 18 19 #define CLOCK_BUFFER_LENGTH 512 20 21 // Commands, original definitions in TensyUSB side code. 22 #define CMD_RESET 'F' // Reset all vars 23 #define CMD_SYNC_SEND 'I' // Send some digits for clock sync 24 #define CMD_SYNC_READOUT 'R' // Read out sync times 25 #define CMD_SYNC_ZERO 'Z' // Initial zero 26 27 28 struct clock_connection { 29 int fd; 30 int endpoint_in; 31 int endpoint_out; 32 int64_t t_base; 33 char buffer[CLOCK_BUFFER_LENGTH]; 34 int minE; 35 int maxE; 36 }; 37 38 39 // Returns microseconds elapsed since boot 40 int64_t uptimeMicros(); 41 42 // Returns microseconds elapsed since last clock sync 43 int micros(struct clock_connection *clk); 44 45 // Runs clock synchronization logic 46 void sync_clocks(struct clock_connection *clk); 47 48 // Run the sync logic without changing clocks, used for estimating clock drift 49 void update_bounds(struct clock_connection *clk); 50 51