Improve accuracy and safety of float serialization - minetest.git

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author	kwolekr <kwolekr@minetest.net>	2015-08-01 01:03:51 -0400
committer	kwolekr <kwolekr@minetest.net>	2015-08-01 19:30:08 -0400
commit	42cf5e972d1e27a92048712bc79806e1a088b96c (patch)
tree	06a717e369b1d0ba5a9d5dfb2e628498d724ade1 /builtin
parent	bf991bde45b279b40fdfa6c6b6fc6e4dd265c7ee (diff)
download	minetest-42cf5e972d1e27a92048712bc79806e1a088b96c.tar.gz minetest-42cf5e972d1e27a92048712bc79806e1a088b96c.tar.bz2 minetest-42cf5e972d1e27a92048712bc79806e1a088b96c.zip

Improve accuracy and safety of float serialization

Multiplying by a factor of 1/1000.f (rather than dividing by 1000.f) directly introduces an error of 1 ULP. With this patch, an exact comparison of a floating point literal with the deserialized F1000 form representing it is now guaranteed to be successful. In addition, the maxmium and minimum safely representible floating point numbers are now well-defined as constants.

Diffstat (limited to 'builtin')

0 files changed, 0 insertions, 0 deletions

/* Minetest Copyright (C) 2017 nerzhul, Loic Blot <loic.blot@unix-experience.fr> This program is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version. This program 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 Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with this program; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. */ #include "modchannels.h" #include <algorithm> #include <cassert> #include "util/basic_macros.h" bool ModChannel::registerConsumer(session_t peer_id) { // ignore if peer_id already joined if (CONTAINS(m_client_consumers, peer_id)) return false; m_client_consumers.push_back(peer_id); return true; } bool ModChannel::removeConsumer(session_t peer_id) { bool found = false; auto peer_removal_fct = [peer_id, &found](u16 p) { if (p == peer_id) found = true; return p == peer_id; }; m_client_consumers.erase( std::remove_if(m_client_consumers.begin(), m_client_consumers.end(), peer_removal_fct), m_client_consumers.end()); return found; } bool ModChannel::canWrite() const { return m_state == MODCHANNEL_STATE_READ_WRITE; } void ModChannel::setState(ModChannelState state) { assert(state != MODCHANNEL_STATE_INIT); m_state = state; } bool ModChannelMgr::channelRegistered(const std::string &channel) const { return m_registered_channels.find(channel) != m_registered_channels.end(); } ModChannel *ModChannelMgr::getModChannel(const std::string &channel) { if (!channelRegistered(channel)) return nullptr; return m_registered_channels[channel].get(); } bool ModChannelMgr::canWriteOnChannel(const std::string &channel) const { const auto channel_it = m_registered_channels.find(channel); if (channel_it == m_registered_channels.end()) { return false; } return channel_it->second->canWrite(); } void ModChannelMgr::registerChannel(const std::string &channel) { m_registered_channels[channel] = std::unique_ptr<ModChannel>(new ModChannel(channel)); } bool ModChannelMgr::setChannelState(const std::string &channel, ModChannelState state) { if (!channelRegistered(channel)) return false; auto channel_it = m_registered_channels.find(channel); channel_it->second->setState(state); return true; } bool ModChannelMgr::removeChannel(const std::string &channel) { if (!channelRegistered(channel)) return false; m_registered_channels.erase(channel); return true; } bool ModChannelMgr::joinChannel(const std::string &channel, session_t peer_id) { if (!channelRegistered(channel)) registerChannel(channel); return m_registered_channels[channel]->registerConsumer(peer_id); } bool ModChannelMgr::leaveChannel(const std::string &channel, session_t peer_id) { if (!channelRegistered(channel)) return false; // Remove consumer from channel bool consumerRemoved = m_registered_channels[channel]->removeConsumer(peer_id); // If channel is empty, remove it if (m_registered_channels[channel]->getChannelPeers().empty()) { removeChannel(channel); } return consumerRemoved; } void ModChannelMgr::leaveAllChannels(session_t peer_id) { for (auto &channel_it : m_registered_channels) channel_it.second->removeConsumer(peer_id); } static std::vector<u16> empty_channel_list; const std::vector<u16> &ModChannelMgr::getChannelPeers(const std::string &channel) const { const auto &channel_it = m_registered_channels.find(channel); if (channel_it == m_registered_channels.end())


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