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Replaced zlib by internal crc32() method (#698)

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Uwe Seimet 2022-02-27 22:24:50 +01:00 committed by GitHub
parent e8f392c3f1
commit 33bfe42017
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2 changed files with 16 additions and 9 deletions
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2
src/raspberrypi/Makefile
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@ -183,7 +183,7 @@ ALL: all
docs: $(DOC_DIR)/rascsi_man_page.txt $(DOC_DIR)/rasctl_man_page.txt $(DOC_DIR)/scsimon_man_page.txt
$(BINDIR)/$(RASCSI): $(SRC_PROTOBUF) $(OBJ_RASCSI) | $(BINDIR)
$(CXX) $(CXXFLAGS) -o $@ $(OBJ_RASCSI) -lpthread -lz -lpcap -lprotobuf -lstdc++fs
$(CXX) $(CXXFLAGS) -o $@ $(OBJ_RASCSI) -lpthread -lpcap -lprotobuf -lstdc++fs
$(BINDIR)/$(RASCTL): $(SRC_PROTOBUF) $(OBJ_RASCTL) | $(BINDIR)
$(CXX) $(CXXFLAGS) -o $@ $(OBJ_RASCTL) -lpthread -lprotobuf -lstdc++fs

23
src/raspberrypi/devices/ctapdriver.cpp
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@ -18,8 +18,6 @@
#include <sys/ioctl.h>
#include <linux/sockios.h>
#endif
// TODO Try to get rid of zlib, there is only one operation using it
#include <zlib.h> // For crc32()
#include "os.h"
#include "ctapdriver.h"
#include "log.h"
@ -447,6 +445,19 @@ bool CTapDriver::PendingPackets()
}
}
// See https://stackoverflow.com/questions/21001659/crc32-algorithm-implementation-in-c-without-a-look-up-table-and-with-a-public-li
uint32_t crc32(BYTE *buf, int length) {
uint32_t crc = 0xffffffff;
for (int i = 0; i < length; i++) {
crc ^= buf[i];
for (int j = 0; j < 8; j++) {
uint32_t mask = -(crc & 1);
crc = (crc >> 1) ^ (0xEDB88320 & mask);
}
}
return ~crc;
}
//---------------------------------------------------------------------------
//
// Receive
@ -457,7 +468,7 @@ int CTapDriver::Rx(BYTE *buf)
ASSERT(m_hTAP != -1);
// Check if there is data that can be received
if(!PendingPackets()){
if (!PendingPackets()) {
return 0;
}
@ -473,11 +484,7 @@ int CTapDriver::Rx(BYTE *buf)
// We need to add the Frame Check Status (FCS) CRC back onto the end of the packet.
// The Linux network subsystem removes it, since most software apps shouldn't ever
// need it.
// Initialize the CRC
DWORD crc = crc32(0L, Z_NULL, 0);
// Calculate the CRC
crc = crc32(crc, buf, dwReceived);
int crc = crc32(buf, dwReceived);
buf[dwReceived + 0] = (BYTE)((crc >> 0) & 0xFF);
buf[dwReceived + 1] = (BYTE)((crc >> 8) & 0xFF);