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Move zigzag encoding function to new common/encoding.c file, add tests

This commit is contained in:
Nicholas Sherlock 2015-02-26 13:27:09 +13:00
parent aae9141120
commit 451d3d7ba2
8 changed files with 164 additions and 21 deletions
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1
Makefile
View File

@ -199,6 +199,7 @@ COMMON_SRC = build_config.c \
common/maths.c \
common/printf.c \
common/typeconversion.c \
common/encoding.c \
main.c \
mw.c \
flight/altitudehold.c \

9
src/main/blackbox/blackbox.c
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@ -26,6 +26,7 @@
#include "common/maths.h"
#include "common/axis.h"
#include "common/color.h"
#include "common/encoding.h"
#include "drivers/gpio.h"
#include "drivers/sensor.h"
@ -878,11 +879,6 @@ static bool sendFieldDefinition(const char * const *headerNames, unsigned int he
*/
static bool blackboxWriteSysinfo()
{
union floatConvert_t {
float f;
uint32_t u;
} floatConvert;
if (xmitState.headerIndex == 0) {
xmitState.u.serialBudget = 0;
xmitState.headerIndex = 1;
@ -937,8 +933,7 @@ static bool blackboxWriteSysinfo()
xmitState.u.serialBudget -= strlen("H maxthrottle:%d\n");
break;
case 8:
floatConvert.f = gyro.scale;
blackboxPrintf("H gyro.scale:0x%x\n", floatConvert.u);
blackboxPrintf("H gyro.scale:0x%x\n", castFloatBytesToInt(gyro.scale));
xmitState.u.serialBudget -= strlen("H gyro.scale:0x\n") + 6;
break;

15
src/main/blackbox/blackbox_io.c
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@ -4,12 +4,13 @@
#include "blackbox_io.h"
#include "platform.h"
#include "version.h"
#include "build_config.h"
#include "common/maths.h"
#include "common/axis.h"
#include "common/color.h"
#include "common/encoding.h"
#include "drivers/gpio.h"
#include "drivers/sensor.h"
@ -144,18 +145,6 @@ void blackboxWriteUnsignedVB(uint32_t value)
blackboxWrite(value);
}
/**
* ZigZag encoding maps all values of a signed integer into those of an unsigned integer in such
* a way that numbers of small absolute value correspond to small integers in the result.
*
* (Compared to just casting a signed to an unsigned which creates huge resulting numbers for
* small negative integers).
*/
static uint32_t zigzagEncode(int32_t value)
{
return (uint32_t)((value << 1) ^ (value >> 31));
}
/**
* Write a signed integer to the blackbox serial port using ZigZig and variable byte encoding.
*/

2
src/main/blackbox/blackbox_io.h
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@ -20,7 +20,7 @@
#include <stdint.h>
#include <stdbool.h>
#include "target.h"
#include "platform.h"
typedef enum BlackboxDevice {
BLACKBOX_DEVICE_SERIAL = 0,

31
src/main/common/encoding.c Normal file
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@ -0,0 +1,31 @@
#include "encoding.h"
/**
* Cast the in-memory representation of the given float directly to an int.
*
* This is useful for printing the hex representation of a float number (which is considerably cheaper
* than a full decimal float formatter, in both code size and output length).
*/
uint32_t castFloatBytesToInt(float f)
{
union floatConvert_t {
float f;
uint32_t u;
} floatConvert;
floatConvert.f = f;
return floatConvert.u;
}
/**
* ZigZag encoding maps all values of a signed integer into those of an unsigned integer in such
* a way that numbers of small absolute value correspond to small integers in the result.
*
* (Compared to just casting a signed to an unsigned which creates huge resulting numbers for
* small negative integers).
*/
uint32_t zigzagEncode(int32_t value)
{
return (uint32_t)((value << 1) ^ (value >> 31));
}

23
src/main/common/encoding.h Normal file
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@ -0,0 +1,23 @@
/*
* This file is part of Cleanflight.
*
* Cleanflight is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* Cleanflight is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with Cleanflight. If not, see <http://www.gnu.org/licenses/>.
*/
#pragma once
#include <stdint.h>
uint32_t castFloatBytesToInt(float f);
uint32_t zigzagEncode(int32_t value);

20
src/test/Makefile
View File

@ -53,6 +53,7 @@ TESTS = \
rc_controls_unittest \
ledstrip_unittest \
ws2811_unittest \
encoding_unittest \
lowpass_unittest
# All Google Test headers. Usually you shouldn't change this
@ -130,6 +131,25 @@ battery_unittest : \
$(OBJECT_DIR)/gtest_main.a
$(CXX) $(CXX_FLAGS) -lpthread $^ -o $(OBJECT_DIR)/$@
$(OBJECT_DIR)/common/encoding.o : $(USER_DIR)/common/encoding.c $(USER_DIR)/common/encoding.h $(GTEST_HEADERS)
@mkdir -p $(dir $@)
$(CC) $(C_FLAGS) $(TEST_CFLAGS) -c $(USER_DIR)/common/encoding.c -o $@
$(OBJECT_DIR)/encoding_unittest.o : \
$(TEST_DIR)/encoding_unittest.cc \
$(USER_DIR)/common/encoding.h \
$(GTEST_HEADERS)
@mkdir -p $(dir $@)
$(CXX) $(CXX_FLAGS) $(TEST_CFLAGS) -c $(TEST_DIR)/encoding_unittest.cc -o $@
encoding_unittest : \
$(OBJECT_DIR)/common/encoding.o \
$(OBJECT_DIR)/encoding_unittest.o \
$(OBJECT_DIR)/gtest_main.a
$(CXX) $(CXX_FLAGS) -lpthread $^ -o $(OBJECT_DIR)/$@
$(OBJECT_DIR)/flight/imu.o : \
$(USER_DIR)/flight/imu.c \

84
src/test/unit/encoding_unittest.cc Normal file
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@ -0,0 +1,84 @@
/*
* This file is part of Cleanflight.
*
* Cleanflight is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* Cleanflight is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with Cleanflight. If not, see <http://www.gnu.org/licenses/>.
*/
#include <stdint.h>
extern "C" {
#include "common/encoding.h"
}
#include "unittest_macros.h"
#include "gtest/gtest.h"
typedef struct zigzagEncodingExpectation_t {
int32_t input;
uint32_t expected;
} zigzagEncodingExpectation_t;
typedef struct floatToIntEncodingExpectation_t {
float input;
uint32_t expected;
} floatToIntEncodingExpectation_t;
TEST(EncodingTest, ZigzagEncodingTest)
{
// given
zigzagEncodingExpectation_t expectations[] = {
{ 0, 0},
{-1, 1},
{ 1, 2},
{-2, 3},
{ 2, 4},
{ 2147483646, 4294967292},
{-2147483647, 4294967293},
{ 2147483647, 4294967294},
{-2147483648, 4294967295},
};
int expectationCount = sizeof(expectations) / sizeof(expectations[0]);
// expect
for (int i = 0; i < expectationCount; i++) {
zigzagEncodingExpectation_t *expectation = &expectations[i];
EXPECT_EQ(expectation->expected, zigzagEncode(expectation->input));
}
}
TEST(EncodingTest, FloatToIntEncodingTest)
{
// given
floatToIntEncodingExpectation_t expectations[] = {
{0.0, 0x00000000},
{2.0, 0x40000000}, // Exponent should be in the top bits
{4.5, 0x40900000}
};
int expectationCount = sizeof(expectations) / sizeof(expectations[0]);
// expect
for (int i = 0; i < expectationCount; i++) {
floatToIntEncodingExpectation_t *expectation = &expectations[i];
EXPECT_EQ(expectation->expected, castFloatBytesToInt(expectation->input));
}
}
// STUBS
extern "C" {
}