WIP/POC: start a test where xtimer uses a fake 'periph_timer' mock implementation

tests/xtimer_mocked_periph_timer/Makefile

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+include ../Makefile.tests_common
+
+TEST_ON_CI_WHITELIST += all
+
+USEMODULE += embunit
+
+# Replace enabling xtimer through the build system to manually enabling it
+# It allows replacing periph_timer implementation for xtimer by including c
+# files
+## USEMODULE += xtimer
+
+# Dependencies
+INCLUDES += -I$(RIOTBASE)/sys/xtimer
+USEMODULE += div
+# Ignore periph_timer dependency it will be mocked
+
+DISABLE_MODULE += auto_init
+
+include $(RIOTBASE)/Makefile.include

tests/xtimer_mocked_periph_timer/main.c

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+/*
+ * Copyright (C) 2018 Freie Universität Berlin
+ *
+ * This file is subject to the terms and conditions of the GNU Lesser
+ * General Public License v2.1. See the file LICENSE in the top level
+ * directory for more details.
+ */
+
+/**
+ * @ingroup     tests
+ * @{
+ *
+ * @file
+ * @brief       xtimer mocked periph_timer test application
+ *
+ * Test xtimer using a mocked implementation of periph_timer
+ *
+ * @author      Gaëtan Harter <gaetan.harter@fu-berlin.de>
+ * @}
+ */
+#include <stdio.h>
+
+#define ENABLE_DEBUG 0
+#include "debug.h"
+
+#include "embUnit.h"
+
+/*
+ * Mock 'xtimer' to use our periph_timer mock implementation
+ * The '.c' files must be included to have access to private functions and
+ * mock with the macros
+ */
+#define timer_init timer_init_mock
+#define timer_read timer_read_mock
+#define timer_set_absolute  timer_set_absolute_mock
+#include "xtimer.h"
+#include "xtimer.c"
+#include "xtimer_core.c"
+
+/* Allow configuring the mock through here */
+#include "periph_timer_mock.h"
+
+
+static void test_timer_cb(void *arg)
+{
+    printf("test_timer_cb(%p)\n", arg);
+}
+
+
+
+/* This is a magic that should tell that it is the first call in
+ * `_xtimer_set`
+ */
+#define TIMER_SET_TICK_COUNT (1)
+
+/*
+ * A magic value that is meant to make it work with the current
+ * implementation
+ */
+#define TIMER_SET_XTIMER_SET_OFFSET (XTIMER_BACKOFF)
+#define TIMER_SET_DESCHEDULE_TIME_TICK (TIMER_SET_XTIMER_SET_OFFSET +1)
+
+/* Simulate descheduling the task for XTIMER_BACKOFF after `_xtimer_now` in
+ * `_xtimer_set_absolute`
+ *
+ * Simulating the de-scheduling with this method assumes we are not in masked
+ * interrupts, which we currently are.
+ * A proper test should just unlock a thread but this is for next step.
+ */
+static int timer_set_deschedule_triggered = 0;
+static void _simulate_deschedule_in_timer_set(uint32_t now)
+{
+    if (now == TIMER_SET_TICK_COUNT && !timer_set_deschedule_triggered) {
+        /* This is countered by being in an interrupt context */
+        DEBUG("De-schedule the thread at %" PRIu32 " for %u\n",
+               now, TIMER_SET_DESCHEDULE_TIME_TICK);
+        timer_set_deschedule_triggered = 1;
+        timer_mock_set(now + TIMER_SET_DESCHEDULE_TIME_TICK);
+    }
+
+}
+static void test_show_xtimer_set_call_target_in_the_past(void)
+{
+    xtimer_init();
+    timer_mock_set_post_read_cb(_simulate_deschedule_in_timer_set);
+
+    xtimer_t timer_low_offset = {.callback = test_timer_cb};
+
+    /* TODO I only handle Freq 1MHz for now in this test */
+    TEST_ASSERT_MESSAGE(XTIMER_HZ == 1000000,
+                        "Only 1Mhz handled here for this first test");
+
+
+    xtimer_set(&timer_low_offset, TIMER_SET_XTIMER_SET_OFFSET);
+
+    /* The test should not be in the `long_list_head` as it is close by */
+    int was_in_list = _remove_timer_from_list(&long_list_head, &timer_low_offset);
+    TEST_ASSERT_MESSAGE(was_in_list == 0,
+                       "The timer has been placed in the long_list_head for a small sleep time");
+}
+
+
+
+/* This is a magic that should tell that it is the first call in
+ * `_xtimer_set_absolute`
+ */
+#define SET_ABSOLUTE_TICK_COUNT (2)
+
+/*
+ * A magic value that is meant to make it work with the current
+ * implementation
+ */
+#define SET_ABSOLUTE_XTIMER_SET_OFFSET (XTIMER_BACKOFF)
+#define SET_ABSOLUTE_DESCHEDULE_TIME_TICK (SET_ABSOLUTE_XTIMER_SET_OFFSET)
+
+/* Simulate descheduling the task for XTIMER_BACKOFF after `_xtimer_now` in
+ * `_xtimer_set_absolute`
+ *
+ * Simulating the de-scheduling with this method assumes we are not in masked
+ * interrupts, which we currently are.
+ * A proper test should just unlock a thread but this is for next step.
+ */
+static int set_absolute_deschedule_triggered = 0;
+static int set_absolute_full_loop = 0;
+static void _simulate_deschedule_in_set_absolute(uint32_t now)
+{
+    if (now == SET_ABSOLUTE_TICK_COUNT && !set_absolute_deschedule_triggered) {
+        /* This is countered by being in an interrupt context */
+        DEBUG("De-schedule the thread at %" PRIu32 " for %u\n",
+               now, SET_ABSOLUTE_DESCHEDULE_TIME_TICK);
+        set_absolute_deschedule_triggered = 1;
+        timer_mock_set(now + SET_ABSOLUTE_DESCHEDULE_TIME_TICK);
+    }
+
+    if (now == 200) {
+        puts("Stuck in xtimer_spin_until for a full loop, jump out");
+        set_absolute_full_loop = 1;
+        /* Step a lot in the future */
+        timer_mock_set((((uint64_t)1) << XTIMER_WIDTH) - 2);
+    }
+}
+
+
+
+/* This test adds delay after the _xtimer_now() in `_xtimer_set_absolute` as if
+ * it was de-scheduled enough time to make `target` in the past.
+ *
+ * This makes `xtimer_spin_until` be called with a target already elapsed.
+ */
+static void test_show_xtimer_set_does_not_handle_overhead(void)
+{
+    xtimer_init();
+    timer_mock_set_post_read_cb(_simulate_deschedule_in_set_absolute);
+
+    xtimer_t timer_low_offset = {.callback = test_timer_cb};
+
+    /* TODO I only handle Freq 1MHz for now in this test */
+    TEST_ASSERT_MESSAGE(XTIMER_HZ == 1000000,
+                        "Only 1Mhz handled here for this first test");
+
+
+    xtimer_set(&timer_low_offset, SET_ABSOLUTE_XTIMER_SET_OFFSET);
+    DEBUG("Outside of xtimer_set\n");
+    TEST_ASSERT(!set_absolute_full_loop);
+}
+
+
+
+static TestRef tests_xtimer_low_level(void)
+{
+    EMB_UNIT_TESTFIXTURES(fixtures) {
+        new_TestFixture(test_show_xtimer_set_call_target_in_the_past),
+        new_TestFixture(test_show_xtimer_set_does_not_handle_overhead),
+
+    };
+    EMB_UNIT_TESTCALLER(xtimer_low_level, NULL, NULL, fixtures);
+
+    return (Test *)&xtimer_low_level;
+}
+
+int main(void)
+{
+    printf("XTIMER_WIDTH: %u\n", XTIMER_WIDTH);
+    printf("XTIMER_HZ: %lu\n", XTIMER_HZ);
+    printf("XTIMER_BACKOFF: %u\n", XTIMER_BACKOFF);
+
+    TESTS_START();
+    TESTS_RUN(tests_xtimer_low_level());
+    TESTS_END();
+    return 0;
+}

tests/xtimer_mocked_periph_timer/periph_timer_mock.c

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+#include <stdint.h>
+
+#define ENABLE_DEBUG 0
+#include "debug.h"
+
+#include "periph/timer.h"
+#include "periph_timer_mock.h"
+
+
+static struct {
+    tim_t dev;
+    unsigned long freq;
+    timer_cb_t cb;
+    void *cb_arg;
+    /* Handle only one channel for now */
+    int channel;
+    unsigned int timeout_value;
+
+    uint32_t current;
+
+    void (*post_read_cb)(uint32_t current);
+} mock_timer;
+
+static void _timer_mock_step_one(void);
+
+
+void timer_mock_set_post_read_cb(void (*post_read_cb)(uint32_t current))
+{
+    mock_timer.post_read_cb = post_read_cb;
+}
+
+uint32_t timer_mock_step(uint32_t ticks)
+{
+    DEBUG("timer_mock_step(%" PRIu32 ") from %" PRIu32 "\n",
+          ticks, mock_timer.current);
+    for (uint32_t i = 0; i < ticks; i++) {
+        _timer_mock_step_one();
+    }
+    return mock_timer.current;
+}
+
+static void _timer_mock_step_one(void)
+{
+    /* TODO handle callbacks for timer */
+    mock_timer.current = (mock_timer.current == mock_timer.timeout_value ?
+                          0 : mock_timer.current + 1);
+    if (mock_timer.current == mock_timer.timeout_value) {
+        printf("periph_timer_mock: TODO Callback not handled\n");
+    }
+}
+
+void timer_mock_set(uint32_t ticks)
+{
+    DEBUG("timer_mock_set(%" PRIu32 ")\n", ticks);
+    /* TODO This should be lower than `mock_timer.timeout_value` to be handled
+     * properly.*/
+    mock_timer.current = ticks;
+}
+
+static void _timer_cb_mock(void *arg, int channel)
+{
+    (void)arg;
+    (void)channel;
+}
+
+/*
+ * Mock of the original functions
+ */
+int timer_init_mock(tim_t dev, unsigned long freq, timer_cb_t cb, void *arg)
+{
+    DEBUG("timer_init_mock(%u): %" PRIu32 ", %p, %p\n", dev, freq, cb, arg);
+
+
+    mock_timer.dev = dev;
+    mock_timer.freq = freq;
+    mock_timer.cb = cb;
+    mock_timer.cb_arg = arg;
+
+    mock_timer.current = 0;
+
+    mock_timer.post_read_cb = NULL;
+
+    (void)_timer_cb_mock;
+
+    return 0;
+}
+
+unsigned int timer_read_mock(tim_t dev)
+{
+    DEBUG("timer_read_mock(%u)\n", dev);
+    uint32_t now = timer_mock_step(1);
+
+    if (mock_timer.post_read_cb) {
+        mock_timer.post_read_cb(now);
+    }
+
+    return now;
+}
+
+int timer_set_absolute_mock(tim_t dev, int channel, unsigned int value)
+{
+    assert(channel == 0); /* Not handled more than one channel for the moment */
+    DEBUG("timer_set_absolute_mock(%u): channel %i, value %u\n", dev, channel, value);
+    mock_timer.channel = channel;
+    mock_timer.timeout_value = value;
+    return 1;
+}

tests/xtimer_mocked_periph_timer/periph_timer_mock.h

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+#ifndef PERIPH_TIMER_MOCK_H
+#define PERIPH_TIMER_MOCK_H
+
+/* Put here any functions that could need to help communicate with the mock */
+
+/*
+ * Step the timer counter by 'ticks' and return the current ticks count after.
+ */
+uint32_t timer_mock_step(uint32_t ticks);
+
+/*
+ * Set the internal timer without handling any callbacks
+ * Should fit the internal precision
+ */
+void timer_mock_set(uint32_t ticks);
+
+/*
+ * This simulates a function that would be called after the value of
+ * `timer_read` is calculated. It is executed after evaluating the return value.
+ */
+void timer_mock_set_post_read_cb(void (*post_read_cb)(uint32_t current));
+
+#endif /* PERIPH_TIMER_MOCK_H */