RfidResearchGroup/proxmark3
1
1
Fork 0
mirror of https://github.com/RfidResearchGroup/proxmark3.git synced 2024-09-20 15:26:13 +08:00
Code Issues Packages Projects Releases Wiki Activity

add: fast reverse 16bit

Browse source
This commit is contained in:
iceman1001 2018-01-27 23:16:35 +01:00
parent e76b4f93b8
commit e396575424
4 changed files with 27 additions and 6 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

21
client/util.c
View file

@ -741,6 +741,27 @@ uint32_t SwapBits(uint32_t v, int b) {
uint8_t reflect8(uint8_t b) {
return ((b * 0x80200802ULL) & 0x0884422110ULL) * 0x0101010101ULL >> 32;
}
uint16_t reflect16(uint16_t b) {
uint16_t v = 0;
v |= (b & 0x8000) >> 15;
v |= (b & 0x4000) >> 13;
v |= (b & 0x2000) >> 11;
v |= (b & 0x1000) >> 9;
v |= (b & 0x0800) >> 7;
v |= (b & 0x0400) >> 5;
v |= (b & 0x0200) >> 3;
v |= (b & 0x0100) >> 1;
v |= (b & 0x0080) << 1;
v |= (b & 0x0040) << 3;
v |= (b & 0x0020) << 5;
v |= (b & 0x0010) << 7;
v |= (b & 0x0008) << 9;
v |= (b & 0x0004) << 11;
v |= (b & 0x0002) << 13;
v |= (b & 0x0001) << 15;
return v;
}
/*
ref http://www.csm.ornl.gov/~dunigan/crc.html
Returns the value v with the bottom b [0,32] bits reflected.

3
client/util.h
View file

@ -204,7 +204,8 @@ extern uint32_t PackBits(uint8_t start, uint8_t len, uint8_t* bits);
extern void rol(uint8_t *data, const size_t len);
extern uint32_t SwapBits(uint32_t value, int nrbits);
extern uint32_t reflect(uint32_t v, int b);
extern uint8_t reflect8(uint8_t b); // dedicated 8bit reversal
extern uint8_t reflect8(uint8_t b); // dedicated 8bit reversal
extern uint16_t reflect16(uint16_t b); // dedicated 16bit reversal
extern uint64_t HornerScheme(uint64_t num, uint64_t divider, uint64_t factor);
extern int num_CPUs(void); // number of logical CPUs

8
common/crc.c
View file

@ -105,7 +105,7 @@ uint32_t CRC8Mad(uint8_t *buff, size_t size) {
crc_init_ref(&crc, 8, 0x1d, 0xe3, 0, true, true);
for ( int i = 0; i < size; ++i)
crc_update2(&crc, buff[i], 8);
return reflect(crc_finish(&crc), 8);
return reflect8(crc_finish(&crc));
}
// width=4 poly=0xC, reversed poly=0x7 init=0x5 refin=true refout=true xorout=0x0000 check= name="CRC-4/LEGIC"
uint32_t CRC4Legic(uint8_t *cmd, size_t size) {
@ -123,7 +123,7 @@ uint32_t CRC8Legic(uint8_t *buff, size_t size) {
crc_init_ref(&crc, 8, 0x63, 0x55, 0, true, true);
for ( int i = 0; i < size; ++i)
crc_update2(&crc, buff[i], 8);
return reflect(crc_finish(&crc), 8);
return reflect8(crc_finish(&crc));
}
// This CRC-16 is used in Legic Advant systems.
@ -138,7 +138,7 @@ uint32_t CRC16Legic(uint8_t *buff, size_t size, uint8_t uidcrc) {
crc_init_ref(&crc, 16, CRC16_POLY_LEGIC, initial, 0, true, true);
for ( int i=0; i < size; ++i)
crc_update(&crc, buff[i], 8);
return reflect(crc_finish(&crc), 16);
return reflect16(crc_finish(&crc));
}
//w=16 poly=0x3d65 init=0x0000 refin=true refout=true xorout=0xffff check=0xea82 name="CRC-16/DNP"
@ -165,7 +165,7 @@ uint32_t CRC16_Iso15693(uint8_t *buff, size_t size) {
crc_init_ref(&crc, 16, 0x8408, 0xFFFF, 0xFFFF, true, false);
for ( int i=0; i < size; ++i)
crc_update(&crc, buff[i], 8);
return reflect(crc_finish(&crc), 16);
return reflect16(crc_finish(&crc));
}
//width=16 poly=0x8408 init=0xffff refin=true refout=true xorout=0x0BC3 check=0xF0B8 name="CRC-16/ICLASS"
uint32_t CRC16_ICLASS(uint8_t *buff, size_t size) {

1
common/iso15693tools.c
View file

@ -28,7 +28,6 @@ uint16_t Iso15693Crc(uint8_t *v, int n)
}
}
}
return ~(uint16_t)(reg & 0xffff);
}