From d76433ade0b75c8cc2b45fdae52a21d7fb28f526 Mon Sep 17 00:00:00 2001
From: Romain Forlot <romain.forlot@iot.bzh>
Date: Sat, 23 Nov 2019 12:42:01 +0100
Subject: decoder/encoder: simplification of code.

- Useless tests removed
- Bit operation changed to more readable ones
- Handle correctly mask to decode signal on 1 byte or in-between bytes more clearly.
- using static_cast now instead of C casting method.
- Avoid manual vector initialization and using default constructors instead.
- Avoid using intermediate variables when this isn't necessary.

Bug-AGL: SPEC-2988

Change-Id: I049d65f460109772b57df7572bdac8e6500242e0
Signed-off-by: Romain Forlot <romain.forlot@iot.bzh>
---
 low-can-binding/can/can-decoder.cpp | 50 ++++++++-----------------------------
 1 file changed, 10 insertions(+), 40 deletions(-)

(limited to 'low-can-binding/can/can-decoder.cpp')

diff --git a/low-can-binding/can/can-decoder.cpp b/low-can-binding/can/can-decoder.cpp
index 76ea79e6..d70f1252 100644
--- a/low-can-binding/can/can-decoder.cpp
+++ b/low-can-binding/can/can-decoder.cpp
@@ -140,8 +140,9 @@ openxc_DynamicField decoder_t::decode_bytes(signal_t& signal, std::shared_ptr<me
 	uint32_t length = message->get_length();
 	uint32_t bit_position = signal.get_bit_position();
 	uint32_t bit_size = signal.get_bit_size();
+
 	std::vector<uint8_t> new_data = std::vector<uint8_t>();
-	new_data.reserve(bit_size << 3);
+	new_data.reserve((bit_size / 8) + 1);
 
 	int new_start_byte = 0;
 	int new_end_byte = 0;
@@ -151,9 +152,7 @@ openxc_DynamicField decoder_t::decode_bytes(signal_t& signal, std::shared_ptr<me
 	converter_t::signal_to_bits_bytes(bit_position, bit_size, new_start_byte, new_end_byte, new_start_bit, new_end_bit);
 
 	if(new_end_byte >= length)
-	{
 		new_end_byte = length-1;
-	}
 
 	if(new_start_byte >= length)
 	{
@@ -161,49 +160,21 @@ openxc_DynamicField decoder_t::decode_bytes(signal_t& signal, std::shared_ptr<me
 		return decoded_value;
 	}
 
-	uint8_t first = data[new_start_byte];
-	int mask_first = 0;
-	for(i=new_start_bit;i<8;i++)
-	{
-		mask_first = mask_first | (1 << i);
-	}
-
-	uint8_t mask_first_v = 0;
-	if(mask_first > 255)
-	{
-		AFB_ERROR("Error mask decode bytes");
-	}
-	else
-	{
-		mask_first_v = (uint8_t)mask_first;
-	}
-
-	data[new_start_byte]=first&mask_first_v;
-
-	uint8_t last = data[new_end_byte];
-	int mask_last = 0;
-	for(i=0;i<=new_end_bit;i++)
-	{
-		mask_last = mask_last | (1 << (7-i));
-	}
+	uint8_t mask_first_v = static_cast<uint8_t>(0xFF << new_start_bit);
+	uint8_t mask_last_v = static_cast<uint8_t>(0xFF >> (7 - new_end_bit));
 
-	uint8_t mask_last_v = 0;
-	if(mask_last > 255)
+	if(new_start_byte == new_end_byte)
 	{
-		AFB_ERROR("Error mask decode bytes");
+		data[new_start_byte] = data[new_start_byte] & (mask_first_v & mask_last_v);
 	}
 	else
 	{
-		mask_last_v = (uint8_t)mask_last;
+		data[new_start_byte] = data[new_start_byte] & mask_first_v;
+		data[new_end_byte] = data[new_end_byte] & mask_last_v;
 	}
 
-	data[new_end_byte]=last&mask_last_v;
-
-
-	for(i=new_start_byte;i<=new_end_byte;i++)
-	{
+	for(i=new_start_byte ; i <= new_end_byte ; i++)
 		new_data.push_back(data[i]);
-	}
 
 	decoded_value = build_DynamicField(new_data);
 
@@ -261,9 +232,8 @@ openxc_DynamicField decoder_t::decode_boolean(signal_t& signal, std::shared_ptr<
 
 	// Don't send if they is no changes
 	if ((signal.get_last_value() == value && !signal.get_send_same()) || !*send )
-	{
 		*send = false;
-	}
+
 	signal.set_last_value(value);
 
 
-- 
cgit 1.2.3-korg