diff --git a/sys/analog_util/adc_util.c b/sys/analog_util/adc_util.c
index af4f480237b2d8a42cf01ab7fad41e1129e12260..ba1ca7c9c40b0f65eec3b6073d8431cfab3e4b88 100644
--- a/sys/analog_util/adc_util.c
+++ b/sys/analog_util/adc_util.c
@@ -1,4 +1,5 @@
/*
+ * Copyright (C) 2018 Eistec AB
* Copyright (C) 2015 Freie Universität Berlin
*
* This file is subject to the terms and conditions of the GNU Lesser
@@ -14,28 +15,58 @@
* @brief ADC utility function implementation
*
* @author Hauke Petersen <hauke.petersen@fu-berlin.de>
+ * @author Joakim Nohlgård <joakim.nohlgard@eistec.se>
*
* @}
*/
+#include <stdint.h>
+#include <inttypes.h>
+
+#include "cpu.h"
+#include "periph/adc.h"
#include "analog_util.h"
+#include "assert.h"
+
+#define ENABLE_DEBUG (0)
+#include "debug.h"
-/* keep a max value to ADC resolution mapping for quick access in the ROM */
-static const int val_max[] = {
- [ADC_RES_6BIT] = 0x003f,
- [ADC_RES_8BIT] = 0x00ff,
- [ADC_RES_10BIT] = 0x03ff,
- [ADC_RES_12BIT] = 0x0fff,
- [ADC_RES_14BIT] = 0x3fff,
- [ADC_RES_16BIT] = 0xffff
-};
+/**
+ * @brief Convert adc_res_t resolution setting into numeric bit count
+ */
+static unsigned int _adc_res_bits(adc_res_t res)
+{
+ switch (res) {
+ case ADC_RES_6BIT:
+ return 6;
+ case ADC_RES_8BIT:
+ return 8;
+ case ADC_RES_10BIT:
+ return 10;
+ case ADC_RES_12BIT:
+ return 12;
+ case ADC_RES_14BIT:
+ return 14;
+ case ADC_RES_16BIT:
+ return 16;
+ default:
+ /* Unsupported ADC resolution, modify your application to use a
+ * different resolution, or add it above */
+ assert(0 == 1);
+ return 0;
+ }
+}
-int adc_util_map(int sample, adc_res_t res, int min, int max)
+int32_t adc_util_map(int sample, adc_res_t res, int32_t min, int32_t max)
{
- return ((((max - min) * sample) / val_max[res]) + min);
+ /* Using 64 bit signed int as intermediate to prevent overflow when range
+ * multiplied by sample requires more than 32 bits */
+ int32_t scaled = (((int64_t)(max - min) * sample) >> _adc_res_bits(res));
+ DEBUG("scaled: %" PRId32 "\n", scaled);
+ return (min + scaled);
}
float adc_util_mapf(int sample, adc_res_t res, float min, float max)
{
- return ((((max - min) * sample) / val_max[res]) + min);
+ return ((((max - min) * sample) / ((int32_t)1L << _adc_res_bits(res))) + min);
}
diff --git a/sys/include/analog_util.h b/sys/include/analog_util.h
index a1cd53fa661913ee754be95fa2b91db36e48bbd0..b3aa408286e11063a18531c38820734f12810f7e 100644
--- a/sys/include/analog_util.h
+++ b/sys/include/analog_util.h
@@ -21,6 +21,8 @@
#ifndef ANALOG_UTIL_H
#define ANALOG_UTIL_H
+#include <stdint.h>
+
#include "periph/adc.h"
#ifdef __cplusplus
@@ -33,8 +35,6 @@ extern "C" {
* This function is useful for converting sampled ADC values into their physical
* representation.
*
- * The min value is asserted to be smaller than the max value.
- *
* @param[in] sample sampled ADC value
* @param[in] res ADC resolution
* @param[in] min the lower bound of the target interval
@@ -42,7 +42,7 @@ extern "C" {
*
* @return the mapped value
*/
-int adc_util_map(int sample, adc_res_t res, int min, int max);
+int32_t adc_util_map(int sample, adc_res_t res, int32_t min, int32_t max);
/**
* @brief Map a sampled ADC value to a given range (using floating point
diff --git a/tests/unittests/tests-analog_util/Makefile b/tests/unittests/tests-analog_util/Makefile
new file mode 100644
index 0000000000000000000000000000000000000000..48422e909a47d7cd428d10fa73825060ccc8d8c2
--- /dev/null
+++ b/tests/unittests/tests-analog_util/Makefile
@@ -0,0 +1 @@
+include $(RIOTBASE)/Makefile.base
diff --git a/tests/unittests/tests-analog_util/Makefile.include b/tests/unittests/tests-analog_util/Makefile.include
new file mode 100644
index 0000000000000000000000000000000000000000..96a45617679176bbbcf9a21eee7af414faa01fb4
--- /dev/null
+++ b/tests/unittests/tests-analog_util/Makefile.include
@@ -0,0 +1 @@
+USEMODULE += analog_util
diff --git a/tests/unittests/tests-analog_util/tests-analog_util.c b/tests/unittests/tests-analog_util/tests-analog_util.c
new file mode 100644
index 0000000000000000000000000000000000000000..a46f1e169fb7dd9d563b9687a11257246717dc4b
--- /dev/null
+++ b/tests/unittests/tests-analog_util/tests-analog_util.c
@@ -0,0 +1,72 @@
+/*
+ * Copyright (C) 2018 Eistec AB
+ *
+ * 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.
+ */
+
+#include "embUnit.h"
+#include "tests-analog_util.h"
+
+#include "analog_util.h"
+
+#define ENABLE_DEBUG (0)
+#include "debug.h"
+
+typedef struct {
+ int32_t expected;
+ int sample;
+ int32_t min;
+ int32_t max;
+ adc_res_t res;
+} test_values_t;
+
+/* Arbitrarily chosen test vectors */
+/* TODO: Choose test vectors in a more qualified manner to catch any edge cases */
+static test_values_t test_data[] = {
+ { 0L, 0, 0L, 10000L, ADC_RES_16BIT},
+ { 1000L, 0, 1000L, 0L, ADC_RES_16BIT},
+ { 65535L, 65535, 0L, 65536L, ADC_RES_16BIT},
+ { 32768L, 128, 0L, 65536L, ADC_RES_8BIT},
+ { 8192L, 128, 0L, 65536L, ADC_RES_10BIT},
+ { 256L, 1, 0L, 65536L, ADC_RES_8BIT},
+ { 65280L, 255, 0L, 65536L, ADC_RES_8BIT},
+ { 1039L, 10, 1000L, 2000L, ADC_RES_8BIT},
+ { 17324L, 3000, 10000L, 20000L, ADC_RES_12BIT},
+ { 11831L, 3000, 10000L, 20000L, ADC_RES_14BIT},
+ { 2301L, 3000, 13L, 50000L, ADC_RES_16BIT},
+ { -134L, 56789, -1000L, 0L, ADC_RES_16BIT},
+ { 16062L, 45671, 30000L, 10000L, ADC_RES_16BIT},
+ { -2535L, 30000, -30000L, 30000L, ADC_RES_16BIT},
+ { 0L, 65535, 65535L, 0L, ADC_RES_16BIT},
+ { 65534L, 1, 65535L, 0L, ADC_RES_16BIT},
+ { 3972L, 9876, 10000L, 0L, ADC_RES_14BIT},
+};
+
+#define TEST_DATA_NUMOF (sizeof(test_data) / sizeof(test_data[0]))
+
+static void test_adc_util_map(void)
+{
+ for (unsigned int k = 0; k < TEST_DATA_NUMOF; ++k) {
+ test_values_t *testp = &test_data[k];
+ int32_t res = adc_util_map(testp->sample, testp->res, testp->min, testp->max);
+ TEST_ASSERT_EQUAL_INT(testp->expected, res);
+ }
+}
+
+Test *tests_adc_util_tests(void)
+{
+ EMB_UNIT_TESTFIXTURES(fixtures) {
+ new_TestFixture(test_adc_util_map),
+ };
+
+ EMB_UNIT_TESTCALLER(adc_util_tests, NULL, NULL, fixtures);
+
+ return (Test *)&adc_util_tests;
+}
+
+void tests_analog_util(void)
+{
+ TESTS_RUN(tests_adc_util_tests());
+}
diff --git a/tests/unittests/tests-analog_util/tests-analog_util.h b/tests/unittests/tests-analog_util/tests-analog_util.h
new file mode 100644
index 0000000000000000000000000000000000000000..273ac33bbf93d5a9bcb8bb20f9920b92f93e3022
--- /dev/null
+++ b/tests/unittests/tests-analog_util/tests-analog_util.h
@@ -0,0 +1,36 @@
+/*
+ * Copyright (C) 2018 Eistec AB
+ *
+ * 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.
+ */
+
+/**
+ * @addtogroup unittests
+ * @{
+ *
+ * @file
+ * @brief Unittests for the ``adc_utils`` header
+ *
+ * @author Joakim Nohlgård <joakim.nohlgard@eistec.se>
+ */
+#ifndef TESTS_ANALOG_UTIL_H
+#define TESTS_ANALOG_UTIL_H
+#include "embUnit/embUnit.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+* @brief The entry point of this test suite.
+*/
+void tests_adc_util(void);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* TESTS_ANALOG_UTIL_H */
+/** @} */