post_events.h

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/*
 * Copyright (c) 2015 The University of Manchester
 *
 * Licensed 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
 *
 *     https://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.
 */
 
#ifndef _POST_EVENTS_H_
#define _POST_EVENTS_H_
 
// Standard includes
#include <stdbool.h>
#include <stdint.h>
 
// Include debug header for log_info etc
#include <debug.h>
 
//---------------------------------------
// Macros
//---------------------------------------
#define MAX_POST_SYNAPTIC_EVENTS 16
 
//---------------------------------------
// Structures
//---------------------------------------
typedef struct {
    uint32_t count_minus_one;
    uint32_t times[MAX_POST_SYNAPTIC_EVENTS];
    post_trace_t traces[MAX_POST_SYNAPTIC_EVENTS];
} post_event_history_t;
 
typedef struct {
    post_trace_t prev_trace;
    uint32_t prev_time;
    const post_trace_t *next_trace;
    const uint32_t *next_time;
    uint32_t num_events;
    uint32_t prev_time_valid;
} post_event_window_t;
 
//---------------------------------------
// Inline functions
//---------------------------------------
 
#if LOG_LEVEL >= LOG_DEBUG
static inline void print_event_history(const post_event_history_t *events) {
    log_debug("      ##  printing entire post event history  ##");
    for (uint32_t i = 0; i <= events->count_minus_one; i++) {
        log_debug("post event: %u, time: %u, trace: %u",
                i, events->times[i], events->traces[i]);
    }
}
#endif
 
static inline post_event_history_t *post_events_init_buffers(
        uint32_t n_neurons) {
    post_event_history_t *post_event_history =
            spin1_malloc(n_neurons * sizeof(post_event_history_t));
    // Check allocations succeeded
    if (post_event_history == NULL) {
        log_error("Unable to allocate global STDP structures - Out of DTCM: Try "
                "reducing the number of neurons per core to fix this problem ");
        return NULL;
    }
 
    // Loop through neurons
    for (uint32_t n = 0; n < n_neurons; n++) {
        // Add initial placeholder entry to buffer
        post_event_history[n].times[0] = 0;
        post_event_history[n].traces[0] = timing_get_initial_post_trace();
        post_event_history[n].count_minus_one = 0;
    }
 
    return post_event_history;
}
 
//---------------------------------------
static inline post_event_window_t post_events_get_window_delayed(
        const post_event_history_t *events, uint32_t begin_time,
        uint32_t end_time) {
    // Start at end event - beyond end of post-event history
    const uint32_t count = events->count_minus_one + 1;
    const uint32_t *end_event_time = events->times + count;
    const uint32_t *event_time = end_event_time;
    const post_trace_t *event_trace = events->traces + count;
 
    post_event_window_t window;
    do {
        // If this event is still in the future, set it as the end
        if (*event_time > end_time) {
            end_event_time = event_time;
        }
 
        // Cache pointer to this event as potential next event and go back one
        // event.
        // **NOTE** next_time can be invalid
        window.next_time = event_time--;
        window.next_trace = event_trace--;
 
        // Keep looping while event occurred after start of window and we
        // haven't hit beginning of array...
    } while (*event_time > begin_time && event_time != events->times);
 
    // Deference event to use as previous
    window.prev_time = *event_time;
    window.prev_trace = *event_trace;
    window.prev_time_valid = event_time != events->times;
 
    // Calculate number of events
    window.num_events = (end_event_time - window.next_time);
 
    // Return window
    return window;
}
 
//---------------------------------------
static inline post_event_window_t post_events_next(
        post_event_window_t window) {
    // Update previous time and increment next time
    window.prev_time = *window.next_time++;
    window.prev_trace = *window.next_trace++;
 
    // Time will now be valid for sure!
    window.prev_time_valid = 1;
 
    // Decrement remaining events
    window.num_events--;
    return window;
}
 
//---------------------------------------
static inline void post_events_add(
        uint32_t time, post_event_history_t *events, post_trace_t trace) {
    if (events->count_minus_one < MAX_POST_SYNAPTIC_EVENTS - 1) {
        // If there's still space, store time at current end
        // and increment count minus 1
        const uint32_t new_index = ++events->count_minus_one;
        events->times[new_index] = time;
        events->traces[new_index] = trace;
    } else {
        // Otherwise Shuffle down elements
        // **NOTE** 1st element is always an entry at time 0
        for (uint32_t e = 2; e < MAX_POST_SYNAPTIC_EVENTS; e++) {
            events->times[e - 1] = events->times[e];
            events->traces[e - 1] = events->traces[e];
        }
 
        // Stick new time at end
        events->times[MAX_POST_SYNAPTIC_EVENTS - 1] = time;
        events->traces[MAX_POST_SYNAPTIC_EVENTS - 1] = trace;
    }
}
 
#if LOG_LEVEL >= LOG_DEBUG
static inline void print_delayed_window_events(
        const post_event_history_t *post_event_history,
        uint32_t begin_time, uint32_t end_time, uint32_t delay_dendritic) {
    log_info("     ##  printing post window  ##");
    post_event_window_t post_window = post_events_get_window_delayed(
            post_event_history, begin_time, end_time);
 
    while (post_window.num_events > 0) {
        const uint32_t delayed_post_time =
                *post_window.next_time + delay_dendritic;
        log_info("post spike: %u, time: %u, trace: %u",
                post_window.num_events, delayed_post_time,
                *post_window.next_trace);
 
        post_window = post_events_next(post_window);
    }
}
#endif
 
#endif  // _POST_EVENTS_H_