From eaba2a7b0658f648bf32219aec0ce827c94333a0 Mon Sep 17 00:00:00 2001
From: David Phillips <david@yeah.nah.nz>
Date: Sat, 27 Feb 2021 22:26:22 +1300
Subject: Make timer mandatory for data manager

The NULL check was a bit of a hack to get the test building. Probably a bad
idea to leave it around, since there's no time it's sane to leave the
timestamps on data manager contexts unset.
---
 Makefile            |  1 +
 data_manager.c      |  6 ++----
 test_data_manager.c | 12 +++++++-----
 timer.c             | 10 ----------
 timer_linux.c       | 29 +++++++++++++++++++++++++++++
 5 files changed, 39 insertions(+), 19 deletions(-)
 create mode 100644 timer_linux.c

diff --git a/Makefile b/Makefile
index 809c153..a1d6ab9 100644
--- a/Makefile
+++ b/Makefile
@@ -62,6 +62,7 @@ TEST_OBJ = \
 	$(NATIVE_DIR)/test_data_manager.o \
 	$(NATIVE_DIR)/data_manager.o \
 	$(NATIVE_DIR)/barometer_sim.o \
+	$(NATIVE_DIR)/timer_linux.o \
 	$(NATIVE_DIR)/util.o
 
 REAL_OBJ = \
diff --git a/data_manager.c b/data_manager.c
index b77ba81..8202216 100644
--- a/data_manager.c
+++ b/data_manager.c
@@ -15,7 +15,7 @@ static float pressure_to_metres_asl(float real, float setting)
 
 void data_manager_init(struct data_ctx *ctx, struct timer *timer, struct barometer *barometer)
 {
-	ctx->setting = 1013.25;
+	ctx->setting = 1013.25; /* FIXME don't hardcode, at least not here */
 	ctx->timer = timer;
 	ctx->barometer = barometer;
 	data_manager_tick(ctx);
@@ -24,9 +24,7 @@ void data_manager_init(struct data_ctx *ctx, struct timer *timer, struct baromet
 void data_manager_tick(struct data_ctx *ctx)
 {
 	/* FIXME altitude rate */
-//	struct data_ctx previous_ctx = *ctx;
-	if (ctx->timer)
-		ctx->timestamp = ctx->timer->get_time();
+	ctx->timestamp = ctx->timer->get_time();
 	ctx->pressure = ctx->barometer->read_pressure();
 	ctx->altitude = pressure_to_metres_asl(ctx->pressure, ctx->setting);
 }
diff --git a/test_data_manager.c b/test_data_manager.c
index 00b5a2a..044282b 100644
--- a/test_data_manager.c
+++ b/test_data_manager.c
@@ -3,6 +3,7 @@
 #include "data_manager.h"
 #include "test_runner.h"
 #include "barometer.h"
+#include "timer.h"
 #include "unity.h"
 
 static int mock_baro_called;
@@ -23,18 +24,19 @@ static struct barometer mock_barometer = {
 RUNNER_DECLARE_TEST(test_data_manager_init_setting)
 {
 	struct data_ctx ctx;
+	struct timer timer;
+	get_system_timer(&timer);
 	reset_mock_get_baro();
-	data_manager_init(&ctx, NULL, &mock_barometer);
+	data_manager_init(&ctx, &timer, &mock_barometer);
 	TEST_ASSERT_EQUAL(1, mock_baro_called);
 }
 
 RUNNER_DECLARE_TEST(test_data_manager_first_readings)
 {
 	struct data_ctx ctx;
-	reset_mock_get_baro();
-	data_manager_init(&ctx, NULL, &mock_barometer);
-	TEST_ASSERT_EQUAL(1, mock_baro_called);
-
+	struct timer timer;
+	get_system_timer(&timer);
+	data_manager_init(&ctx, &timer, &mock_barometer);
 
 	reset_mock_get_baro();
 	data_manager_tick(&ctx);
diff --git a/timer.c b/timer.c
index 7d82b0f..498e621 100644
--- a/timer.c
+++ b/timer.c
@@ -11,9 +11,6 @@
  * interrupts already disabled in order to be safe
  */
 
-/* XXX hardcoded based upon TCCR3B selecting /256 prescaled clock */
-#define TIMER_HZ (F_CPU / 256)
-
 static void timer_init(void)
 {
 	/* timer1 has /1024 prescaler, 1 Hz comparator val, enable IRQ */
@@ -28,18 +25,11 @@ static void timer_init(void)
 	TCCR3B |= (1 << CS32);
 }
 
-static float timer_stamps_to_seconds(uint16_t start, uint16_t end)
-{
-	return (float)(end - start) / TIMER_HZ;
-}
-
 static uint16_t timer_get_value(void)
 {
 	return TCNT3;
 }
 
-/**/
-
 void get_system_timer(struct timer *timer)
 {
 	timer->init = timer_init;
diff --git a/timer_linux.c b/timer_linux.c
new file mode 100644
index 0000000..56886e3
--- /dev/null
+++ b/timer_linux.c
@@ -0,0 +1,29 @@
+#include <time.h>
+#include <stdint.h>
+
+#include "timer.h"
+
+/* On POSIX, we emulate a monotonic 16-bit timer for timestamping events in
+ * lieu of timer3 on the AVR.
+ */
+
+static void timer_init(void)
+{
+	/* do nothing */
+}
+
+static uint16_t timer_get_value(void)
+{
+	struct timespec ts;
+	clock_gettime(CLOCK_MONOTONIC, &ts);
+	/* FIXME abort on error */
+	/* return milliseconds as uint16_t, truncating the rest */
+	return ts.tv_nsec / 1e6;
+}
+
+
+void get_system_timer(struct timer *timer)
+{
+	timer->init = timer_init;
+	timer->get_time = timer_get_value;
+}
-- 
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