# LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
# NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
# SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-########################################################################
-# Function API:
-# UINT16 crc_t10dif_pcl(
-# UINT16 init_crc, //initial CRC value, 16 bits
-# const unsigned char *buf, //buffer pointer to calculate CRC on
-# UINT64 len //buffer length in bytes (64-bit data)
-# );
#
# Reference paper titled "Fast CRC Computation for Generic
# Polynomials Using PCLMULQDQ Instruction"
# URL: http://www.intel.com/content/dam/www/public/us/en/documents
# /white-papers/fast-crc-computation-generic-polynomials-pclmulqdq-paper.pdf
#
-#
#include <linux/linkage.h>
.text
-#define arg1 %rdi
-#define arg2 %rsi
-#define arg3 %rdx
-
-#define arg1_low32 %edi
+#define init_crc %edi
+#define buf %rsi
+#define len %rdx
+
+#define FOLD_CONSTS %xmm10
+#define BSWAP_MASK %xmm11
+
+# Fold reg1, reg2 into the next 32 data bytes, storing the result back into
+# reg1, reg2.
+.macro fold_32_bytes offset, reg1, reg2
+ movdqu \offset(buf), %xmm9
+ movdqu \offset+16(buf), %xmm12
+ pshufb BSWAP_MASK, %xmm9
+ pshufb BSWAP_MASK, %xmm12
+ movdqa \reg1, %xmm8
+ movdqa \reg2, %xmm13
+ pclmulqdq $0x00, FOLD_CONSTS, \reg1
+ pclmulqdq $0x11, FOLD_CONSTS, %xmm8
+ pclmulqdq $0x00, FOLD_CONSTS, \reg2
+ pclmulqdq $0x11, FOLD_CONSTS, %xmm13
+ pxor %xmm9 , \reg1
+ xorps %xmm8 , \reg1
+ pxor %xmm12, \reg2
+ xorps %xmm13, \reg2
+.endm
+
+# Fold src_reg into dst_reg.
+.macro fold_16_bytes src_reg, dst_reg
+ movdqa \src_reg, %xmm8
+ pclmulqdq $0x11, FOLD_CONSTS, \src_reg
+ pclmulqdq $0x00, FOLD_CONSTS, %xmm8
+ pxor %xmm8, \dst_reg
+ xorps \src_reg, \dst_reg
+.endm
-ENTRY(crc_t10dif_pcl)
+#
+# u16 crc_t10dif_pcl(u16 init_crc, const *u8 buf, size_t len);
+#
+# Assumes len >= 16.
+#
.align 16
+ENTRY(crc_t10dif_pcl)
- # adjust the 16-bit initial_crc value, scale it to 32 bits
- shl $16, arg1_low32
-
- # Allocate Stack Space
- mov %rsp, %rcx
- sub $16*2, %rsp
- # align stack to 16 byte boundary
- and $~(0x10 - 1), %rsp
-
- # check if smaller than 256
- cmp $256, arg3
-
- # for sizes less than 128, we can't fold 64B at a time...
- jl _less_than_128
-
-
- # load the initial crc value
- movd arg1_low32, %xmm10 # initial crc
-
- # crc value does not need to be byte-reflected, but it needs
- # to be moved to the high part of the register.
- # because data will be byte-reflected and will align with
- # initial crc at correct place.
- pslldq $12, %xmm10
-
- movdqa SHUF_MASK(%rip), %xmm11
- # receive the initial 64B data, xor the initial crc value
- movdqu 16*0(arg2), %xmm0
- movdqu 16*1(arg2), %xmm1
- movdqu 16*2(arg2), %xmm2
- movdqu 16*3(arg2), %xmm3
- movdqu 16*4(arg2), %xmm4
- movdqu 16*5(arg2), %xmm5
- movdqu 16*6(arg2), %xmm6
- movdqu 16*7(arg2), %xmm7
-
- pshufb %xmm11, %xmm0
- # XOR the initial_crc value
- pxor %xmm10, %xmm0
- pshufb %xmm11, %xmm1
- pshufb %xmm11, %xmm2
- pshufb %xmm11, %xmm3
- pshufb %xmm11, %xmm4
- pshufb %xmm11, %xmm5
- pshufb %xmm11, %xmm6
- pshufb %xmm11, %xmm7
-
- movdqa rk3(%rip), %xmm10 #xmm10 has rk3 and rk4
- #imm value of pclmulqdq instruction
- #will determine which constant to use
-
- #################################################################
- # we subtract 256 instead of 128 to save one instruction from the loop
- sub $256, arg3
-
- # at this section of the code, there is 64*x+y (0<=y<64) bytes of
- # buffer. The _fold_64_B_loop will fold 64B at a time
- # until we have 64+y Bytes of buffer
-
-
- # fold 64B at a time. This section of the code folds 4 xmm
- # registers in parallel
-_fold_64_B_loop:
-
- # update the buffer pointer
- add $128, arg2 # buf += 64#
-
- movdqu 16*0(arg2), %xmm9
- movdqu 16*1(arg2), %xmm12
- pshufb %xmm11, %xmm9
- pshufb %xmm11, %xmm12
- movdqa %xmm0, %xmm8
- movdqa %xmm1, %xmm13
- pclmulqdq $0x0 , %xmm10, %xmm0
- pclmulqdq $0x11, %xmm10, %xmm8
- pclmulqdq $0x0 , %xmm10, %xmm1
- pclmulqdq $0x11, %xmm10, %xmm13
- pxor %xmm9 , %xmm0
- xorps %xmm8 , %xmm0
- pxor %xmm12, %xmm1
- xorps %xmm13, %xmm1
-
- movdqu 16*2(arg2), %xmm9
- movdqu 16*3(arg2), %xmm12
- pshufb %xmm11, %xmm9
- pshufb %xmm11, %xmm12
- movdqa %xmm2, %xmm8
- movdqa %xmm3, %xmm13
- pclmulqdq $0x0, %xmm10, %xmm2
- pclmulqdq $0x11, %xmm10, %xmm8
- pclmulqdq $0x0, %xmm10, %xmm3
- pclmulqdq $0x11, %xmm10, %xmm13
- pxor %xmm9 , %xmm2
- xorps %xmm8 , %xmm2
- pxor %xmm12, %xmm3
- xorps %xmm13, %xmm3
-
- movdqu 16*4(arg2), %xmm9
- movdqu 16*5(arg2), %xmm12
- pshufb %xmm11, %xmm9
- pshufb %xmm11, %xmm12
- movdqa %xmm4, %xmm8
- movdqa %xmm5, %xmm13
- pclmulqdq $0x0, %xmm10, %xmm4
- pclmulqdq $0x11, %xmm10, %xmm8
- pclmulqdq $0x0, %xmm10, %xmm5
- pclmulqdq $0x11, %xmm10, %xmm13
- pxor %xmm9 , %xmm4
- xorps %xmm8 , %xmm4
- pxor %xmm12, %xmm5
- xorps %xmm13, %xmm5
-
- movdqu 16*6(arg2), %xmm9
- movdqu 16*7(arg2), %xmm12
- pshufb %xmm11, %xmm9
- pshufb %xmm11, %xmm12
- movdqa %xmm6 , %xmm8
- movdqa %xmm7 , %xmm13
- pclmulqdq $0x0 , %xmm10, %xmm6
- pclmulqdq $0x11, %xmm10, %xmm8
- pclmulqdq $0x0 , %xmm10, %xmm7
- pclmulqdq $0x11, %xmm10, %xmm13
- pxor %xmm9 , %xmm6
- xorps %xmm8 , %xmm6
- pxor %xmm12, %xmm7
- xorps %xmm13, %xmm7
-
- sub $128, arg3
-
- # check if there is another 64B in the buffer to be able to fold
- jge _fold_64_B_loop
- ##################################################################
-
-
- add $128, arg2
- # at this point, the buffer pointer is pointing at the last y Bytes
- # of the buffer the 64B of folded data is in 4 of the xmm
- # registers: xmm0, xmm1, xmm2, xmm3
-
-
- # fold the 8 xmm registers to 1 xmm register with different constants
-
- movdqa rk9(%rip), %xmm10
- movdqa %xmm0, %xmm8
- pclmulqdq $0x11, %xmm10, %xmm0
- pclmulqdq $0x0 , %xmm10, %xmm8
- pxor %xmm8, %xmm7
- xorps %xmm0, %xmm7
-
- movdqa rk11(%rip), %xmm10
- movdqa %xmm1, %xmm8
- pclmulqdq $0x11, %xmm10, %xmm1
- pclmulqdq $0x0 , %xmm10, %xmm8
- pxor %xmm8, %xmm7
- xorps %xmm1, %xmm7
-
- movdqa rk13(%rip), %xmm10
- movdqa %xmm2, %xmm8
- pclmulqdq $0x11, %xmm10, %xmm2
- pclmulqdq $0x0 , %xmm10, %xmm8
- pxor %xmm8, %xmm7
- pxor %xmm2, %xmm7
-
- movdqa rk15(%rip), %xmm10
- movdqa %xmm3, %xmm8
- pclmulqdq $0x11, %xmm10, %xmm3
- pclmulqdq $0x0 , %xmm10, %xmm8
- pxor %xmm8, %xmm7
- xorps %xmm3, %xmm7
-
- movdqa rk17(%rip), %xmm10
- movdqa %xmm4, %xmm8
- pclmulqdq $0x11, %xmm10, %xmm4
- pclmulqdq $0x0 , %xmm10, %xmm8
- pxor %xmm8, %xmm7
- pxor %xmm4, %xmm7
-
- movdqa rk19(%rip), %xmm10
- movdqa %xmm5, %xmm8
- pclmulqdq $0x11, %xmm10, %xmm5
- pclmulqdq $0x0 , %xmm10, %xmm8
- pxor %xmm8, %xmm7
- xorps %xmm5, %xmm7
-
- movdqa rk1(%rip), %xmm10 #xmm10 has rk1 and rk2
- #imm value of pclmulqdq instruction
- #will determine which constant to use
- movdqa %xmm6, %xmm8
- pclmulqdq $0x11, %xmm10, %xmm6
- pclmulqdq $0x0 , %xmm10, %xmm8
- pxor %xmm8, %xmm7
- pxor %xmm6, %xmm7
-
-
- # instead of 64, we add 48 to the loop counter to save 1 instruction
- # from the loop instead of a cmp instruction, we use the negative
- # flag with the jl instruction
- add $128-16, arg3
- jl _final_reduction_for_128
-
- # now we have 16+y bytes left to reduce. 16 Bytes is in register xmm7
- # and the rest is in memory. We can fold 16 bytes at a time if y>=16
- # continue folding 16B at a time
-
-_16B_reduction_loop:
+ movdqa .Lbswap_mask(%rip), BSWAP_MASK
+
+ # For sizes less than 256 bytes, we can't fold 128 bytes at a time.
+ cmp $256, len
+ jl .Lless_than_256_bytes
+
+ # Load the first 128 data bytes. Byte swapping is necessary to make the
+ # bit order match the polynomial coefficient order.
+ movdqu 16*0(buf), %xmm0
+ movdqu 16*1(buf), %xmm1
+ movdqu 16*2(buf), %xmm2
+ movdqu 16*3(buf), %xmm3
+ movdqu 16*4(buf), %xmm4
+ movdqu 16*5(buf), %xmm5
+ movdqu 16*6(buf), %xmm6
+ movdqu 16*7(buf), %xmm7
+ add $128, buf
+ pshufb BSWAP_MASK, %xmm0
+ pshufb BSWAP_MASK, %xmm1
+ pshufb BSWAP_MASK, %xmm2
+ pshufb BSWAP_MASK, %xmm3
+ pshufb BSWAP_MASK, %xmm4
+ pshufb BSWAP_MASK, %xmm5
+ pshufb BSWAP_MASK, %xmm6
+ pshufb BSWAP_MASK, %xmm7
+
+ # XOR the first 16 data *bits* with the initial CRC value.
+ pxor %xmm8, %xmm8
+ pinsrw $7, init_crc, %xmm8
+ pxor %xmm8, %xmm0
+
+ movdqa .Lfold_across_128_bytes_consts(%rip), FOLD_CONSTS
+
+ # Subtract 128 for the 128 data bytes just consumed. Subtract another
+ # 128 to simplify the termination condition of the following loop.
+ sub $256, len
+
+ # While >= 128 data bytes remain (not counting xmm0-7), fold the 128
+ # bytes xmm0-7 into them, storing the result back into xmm0-7.
+.Lfold_128_bytes_loop:
+ fold_32_bytes 0, %xmm0, %xmm1
+ fold_32_bytes 32, %xmm2, %xmm3
+ fold_32_bytes 64, %xmm4, %xmm5
+ fold_32_bytes 96, %xmm6, %xmm7
+ add $128, buf
+ sub $128, len
+ jge .Lfold_128_bytes_loop
+
+ # Now fold the 112 bytes in xmm0-xmm6 into the 16 bytes in xmm7.
+
+ # Fold across 64 bytes.
+ movdqa .Lfold_across_64_bytes_consts(%rip), FOLD_CONSTS
+ fold_16_bytes %xmm0, %xmm4
+ fold_16_bytes %xmm1, %xmm5
+ fold_16_bytes %xmm2, %xmm6
+ fold_16_bytes %xmm3, %xmm7
+ # Fold across 32 bytes.
+ movdqa .Lfold_across_32_bytes_consts(%rip), FOLD_CONSTS
+ fold_16_bytes %xmm4, %xmm6
+ fold_16_bytes %xmm5, %xmm7
+ # Fold across 16 bytes.
+ movdqa .Lfold_across_16_bytes_consts(%rip), FOLD_CONSTS
+ fold_16_bytes %xmm6, %xmm7
+
+ # Add 128 to get the correct number of data bytes remaining in 0...127
+ # (not counting xmm7), following the previous extra subtraction by 128.
+ # Then subtract 16 to simplify the termination condition of the
+ # following loop.
+ add $128-16, len
+
+ # While >= 16 data bytes remain (not counting xmm7), fold the 16 bytes
+ # xmm7 into them, storing the result back into xmm7.
+ jl .Lfold_16_bytes_loop_done
+.Lfold_16_bytes_loop:
movdqa %xmm7, %xmm8
- pclmulqdq $0x11, %xmm10, %xmm7
- pclmulqdq $0x0 , %xmm10, %xmm8
+ pclmulqdq $0x11, FOLD_CONSTS, %xmm7
+ pclmulqdq $0x00, FOLD_CONSTS, %xmm8
pxor %xmm8, %xmm7
- movdqu (arg2), %xmm0
- pshufb %xmm11, %xmm0
+ movdqu (buf), %xmm0
+ pshufb BSWAP_MASK, %xmm0
pxor %xmm0 , %xmm7
- add $16, arg2
- sub $16, arg3
- # instead of a cmp instruction, we utilize the flags with the
- # jge instruction equivalent of: cmp arg3, 16-16
- # check if there is any more 16B in the buffer to be able to fold
- jge _16B_reduction_loop
-
- #now we have 16+z bytes left to reduce, where 0<= z < 16.
- #first, we reduce the data in the xmm7 register
-
-
-_final_reduction_for_128:
- # check if any more data to fold. If not, compute the CRC of
- # the final 128 bits
- add $16, arg3
- je _128_done
-
- # here we are getting data that is less than 16 bytes.
- # since we know that there was data before the pointer, we can
- # offset the input pointer before the actual point, to receive
- # exactly 16 bytes. after that the registers need to be adjusted.
-_get_last_two_xmms:
+ add $16, buf
+ sub $16, len
+ jge .Lfold_16_bytes_loop
+
+.Lfold_16_bytes_loop_done:
+ # Add 16 to get the correct number of data bytes remaining in 0...15
+ # (not counting xmm7), following the previous extra subtraction by 16.
+ add $16, len
+ je .Lreduce_final_16_bytes
+
+.Lhandle_partial_segment:
+ # Reduce the last '16 + len' bytes where 1 <= len <= 15 and the first 16
+ # bytes are in xmm7 and the rest are the remaining data in 'buf'. To do
+ # this without needing a fold constant for each possible 'len', redivide
+ # the bytes into a first chunk of 'len' bytes and a second chunk of 16
+ # bytes, then fold the first chunk into the second.
+
movdqa %xmm7, %xmm2
- movdqu -16(arg2, arg3), %xmm1
- pshufb %xmm11, %xmm1
+ # xmm1 = last 16 original data bytes
+ movdqu -16(buf, len), %xmm1
+ pshufb BSWAP_MASK, %xmm1
- # get rid of the extra data that was loaded before
- # load the shift constant
- lea pshufb_shf_table+16(%rip), %rax
- sub arg3, %rax
+ # xmm2 = high order part of second chunk: xmm7 left-shifted by 'len' bytes.
+ lea .Lbyteshift_table+16(%rip), %rax
+ sub len, %rax
movdqu (%rax), %xmm0
-
- # shift xmm2 to the left by arg3 bytes
pshufb %xmm0, %xmm2
- # shift xmm7 to the right by 16-arg3 bytes
- pxor mask1(%rip), %xmm0
+ # xmm7 = first chunk: xmm7 right-shifted by '16-len' bytes.
+ pxor .Lmask1(%rip), %xmm0
pshufb %xmm0, %xmm7
+
+ # xmm1 = second chunk: 'len' bytes from xmm1 (low-order bytes),
+ # then '16-len' bytes from xmm2 (high-order bytes).
pblendvb %xmm2, %xmm1 #xmm0 is implicit
- # fold 16 Bytes
- movdqa %xmm1, %xmm2
+ # Fold the first chunk into the second chunk, storing the result in xmm7.
movdqa %xmm7, %xmm8
- pclmulqdq $0x11, %xmm10, %xmm7
- pclmulqdq $0x0 , %xmm10, %xmm8
+ pclmulqdq $0x11, FOLD_CONSTS, %xmm7
+ pclmulqdq $0x00, FOLD_CONSTS, %xmm8
pxor %xmm8, %xmm7
- pxor %xmm2, %xmm7
+ pxor %xmm1, %xmm7
-_128_done:
- # compute crc of a 128-bit value
- movdqa rk5(%rip), %xmm10 # rk5 and rk6 in xmm10
- movdqa %xmm7, %xmm0
+.Lreduce_final_16_bytes:
+ # Reduce the 128-bit value M(x), stored in xmm7, to the final 16-bit CRC
- #64b fold
- pclmulqdq $0x1, %xmm10, %xmm7
- pslldq $8 , %xmm0
- pxor %xmm0, %xmm7
+ # Load 'x^48 * (x^48 mod G(x))' and 'x^48 * (x^80 mod G(x))'.
+ movdqa .Lfinal_fold_consts(%rip), FOLD_CONSTS
- #32b fold
+ # Fold the high 64 bits into the low 64 bits, while also multiplying by
+ # x^64. This produces a 128-bit value congruent to x^64 * M(x) and
+ # whose low 48 bits are 0.
movdqa %xmm7, %xmm0
+ pclmulqdq $0x11, FOLD_CONSTS, %xmm7 # high bits * x^48 * (x^80 mod G(x))
+ pslldq $8, %xmm0
+ pxor %xmm0, %xmm7 # + low bits * x^64
- pand mask2(%rip), %xmm0
-
- psrldq $12, %xmm7
- pclmulqdq $0x10, %xmm10, %xmm7
- pxor %xmm0, %xmm7
-
- #barrett reduction
-_barrett:
- movdqa rk7(%rip), %xmm10 # rk7 and rk8 in xmm10
+ # Fold the high 32 bits into the low 96 bits. This produces a 96-bit
+ # value congruent to x^64 * M(x) and whose low 48 bits are 0.
movdqa %xmm7, %xmm0
- pclmulqdq $0x01, %xmm10, %xmm7
- pslldq $4, %xmm7
- pclmulqdq $0x11, %xmm10, %xmm7
+ pand .Lmask2(%rip), %xmm0 # zero high 32 bits
+ psrldq $12, %xmm7 # extract high 32 bits
+ pclmulqdq $0x00, FOLD_CONSTS, %xmm7 # high 32 bits * x^48 * (x^48 mod G(x))
+ pxor %xmm0, %xmm7 # + low bits
- pslldq $4, %xmm7
- pxor %xmm0, %xmm7
- pextrd $1, %xmm7, %eax
+ # Load G(x) and floor(x^48 / G(x)).
+ movdqa .Lbarrett_reduction_consts(%rip), FOLD_CONSTS
-_cleanup:
- # scale the result back to 16 bits
- shr $16, %eax
- mov %rcx, %rsp
+ # Use Barrett reduction to compute the final CRC value.
+ movdqa %xmm7, %xmm0
+ pclmulqdq $0x11, FOLD_CONSTS, %xmm7 # high 32 bits * floor(x^48 / G(x))
+ psrlq $32, %xmm7 # /= x^32
+ pclmulqdq $0x00, FOLD_CONSTS, %xmm7 # *= G(x)
+ psrlq $48, %xmm0
+ pxor %xmm7, %xmm0 # + low 16 nonzero bits
+ # Final CRC value (x^16 * M(x)) mod G(x) is in low 16 bits of xmm0.
+
+ pextrw $0, %xmm0, %eax
ret
-########################################################################
-
.align 16
-_less_than_128:
-
- # check if there is enough buffer to be able to fold 16B at a time
- cmp $32, arg3
- jl _less_than_32
- movdqa SHUF_MASK(%rip), %xmm11
+.Lless_than_256_bytes:
+ # Checksumming a buffer of length 16...255 bytes
- # now if there is, load the constants
- movdqa rk1(%rip), %xmm10 # rk1 and rk2 in xmm10
+ # Load the first 16 data bytes.
+ movdqu (buf), %xmm7
+ pshufb BSWAP_MASK, %xmm7
+ add $16, buf
- movd arg1_low32, %xmm0 # get the initial crc value
- pslldq $12, %xmm0 # align it to its correct place
- movdqu (arg2), %xmm7 # load the plaintext
- pshufb %xmm11, %xmm7 # byte-reflect the plaintext
+ # XOR the first 16 data *bits* with the initial CRC value.
+ pxor %xmm0, %xmm0
+ pinsrw $7, init_crc, %xmm0
pxor %xmm0, %xmm7
-
- # update the buffer pointer
- add $16, arg2
-
- # update the counter. subtract 32 instead of 16 to save one
- # instruction from the loop
- sub $32, arg3
-
- jmp _16B_reduction_loop
-
-
-.align 16
-_less_than_32:
- # mov initial crc to the return value. this is necessary for
- # zero-length buffers.
- mov arg1_low32, %eax
- test arg3, arg3
- je _cleanup
-
- movdqa SHUF_MASK(%rip), %xmm11
-
- movd arg1_low32, %xmm0 # get the initial crc value
- pslldq $12, %xmm0 # align it to its correct place
-
- cmp $16, arg3
- je _exact_16_left
- jl _less_than_16_left
-
- movdqu (arg2), %xmm7 # load the plaintext
- pshufb %xmm11, %xmm7 # byte-reflect the plaintext
- pxor %xmm0 , %xmm7 # xor the initial crc value
- add $16, arg2
- sub $16, arg3
- movdqa rk1(%rip), %xmm10 # rk1 and rk2 in xmm10
- jmp _get_last_two_xmms
-
-
-.align 16
-_less_than_16_left:
- # use stack space to load data less than 16 bytes, zero-out
- # the 16B in memory first.
-
- pxor %xmm1, %xmm1
- mov %rsp, %r11
- movdqa %xmm1, (%r11)
-
- cmp $4, arg3
- jl _only_less_than_4
-
- # backup the counter value
- mov arg3, %r9
- cmp $8, arg3
- jl _less_than_8_left
-
- # load 8 Bytes
- mov (arg2), %rax
- mov %rax, (%r11)
- add $8, %r11
- sub $8, arg3
- add $8, arg2
-_less_than_8_left:
-
- cmp $4, arg3
- jl _less_than_4_left
-
- # load 4 Bytes
- mov (arg2), %eax
- mov %eax, (%r11)
- add $4, %r11
- sub $4, arg3
- add $4, arg2
-_less_than_4_left:
-
- cmp $2, arg3
- jl _less_than_2_left
-
- # load 2 Bytes
- mov (arg2), %ax
- mov %ax, (%r11)
- add $2, %r11
- sub $2, arg3
- add $2, arg2
-_less_than_2_left:
- cmp $1, arg3
- jl _zero_left
-
- # load 1 Byte
- mov (arg2), %al
- mov %al, (%r11)
-_zero_left:
- movdqa (%rsp), %xmm7
- pshufb %xmm11, %xmm7
- pxor %xmm0 , %xmm7 # xor the initial crc value
-
- # shl r9, 4
- lea pshufb_shf_table+16(%rip), %rax
- sub %r9, %rax
- movdqu (%rax), %xmm0
- pxor mask1(%rip), %xmm0
-
- pshufb %xmm0, %xmm7
- jmp _128_done
-
-.align 16
-_exact_16_left:
- movdqu (arg2), %xmm7
- pshufb %xmm11, %xmm7
- pxor %xmm0 , %xmm7 # xor the initial crc value
-
- jmp _128_done
-
-_only_less_than_4:
- cmp $3, arg3
- jl _only_less_than_3
-
- # load 3 Bytes
- mov (arg2), %al
- mov %al, (%r11)
-
- mov 1(arg2), %al
- mov %al, 1(%r11)
-
- mov 2(arg2), %al
- mov %al, 2(%r11)
-
- movdqa (%rsp), %xmm7
- pshufb %xmm11, %xmm7
- pxor %xmm0 , %xmm7 # xor the initial crc value
-
- psrldq $5, %xmm7
-
- jmp _barrett
-_only_less_than_3:
- cmp $2, arg3
- jl _only_less_than_2
-
- # load 2 Bytes
- mov (arg2), %al
- mov %al, (%r11)
-
- mov 1(arg2), %al
- mov %al, 1(%r11)
-
- movdqa (%rsp), %xmm7
- pshufb %xmm11, %xmm7
- pxor %xmm0 , %xmm7 # xor the initial crc value
-
- psrldq $6, %xmm7
-
- jmp _barrett
-_only_less_than_2:
-
- # load 1 Byte
- mov (arg2), %al
- mov %al, (%r11)
-
- movdqa (%rsp), %xmm7
- pshufb %xmm11, %xmm7
- pxor %xmm0 , %xmm7 # xor the initial crc value
-
- psrldq $7, %xmm7
-
- jmp _barrett
-
+ movdqa .Lfold_across_16_bytes_consts(%rip), FOLD_CONSTS
+ cmp $16, len
+ je .Lreduce_final_16_bytes # len == 16
+ sub $32, len
+ jge .Lfold_16_bytes_loop # 32 <= len <= 255
+ add $16, len
+ jmp .Lhandle_partial_segment # 17 <= len <= 31
ENDPROC(crc_t10dif_pcl)
.section .rodata, "a", @progbits
.align 16
-# precomputed constants
-# these constants are precomputed from the poly:
-# 0x8bb70000 (0x8bb7 scaled to 32 bits)
-# Q = 0x18BB70000
-# rk1 = 2^(32*3) mod Q << 32
-# rk2 = 2^(32*5) mod Q << 32
-# rk3 = 2^(32*15) mod Q << 32
-# rk4 = 2^(32*17) mod Q << 32
-# rk5 = 2^(32*3) mod Q << 32
-# rk6 = 2^(32*2) mod Q << 32
-# rk7 = floor(2^64/Q)
-# rk8 = Q
-rk1:
-.quad 0x2d56000000000000
-rk2:
-.quad 0x06df000000000000
-rk3:
-.quad 0x9d9d000000000000
-rk4:
-.quad 0x7cf5000000000000
-rk5:
-.quad 0x2d56000000000000
-rk6:
-.quad 0x1368000000000000
-rk7:
-.quad 0x00000001f65a57f8
-rk8:
-.quad 0x000000018bb70000
-
-rk9:
-.quad 0xceae000000000000
-rk10:
-.quad 0xbfd6000000000000
-rk11:
-.quad 0x1e16000000000000
-rk12:
-.quad 0x713c000000000000
-rk13:
-.quad 0xf7f9000000000000
-rk14:
-.quad 0x80a6000000000000
-rk15:
-.quad 0x044c000000000000
-rk16:
-.quad 0xe658000000000000
-rk17:
-.quad 0xad18000000000000
-rk18:
-.quad 0xa497000000000000
-rk19:
-.quad 0x6ee3000000000000
-rk20:
-.quad 0xe7b5000000000000
-
+# Fold constants precomputed from the polynomial 0x18bb7
+# G(x) = x^16 + x^15 + x^11 + x^9 + x^8 + x^7 + x^5 + x^4 + x^2 + x^1 + x^0
+.Lfold_across_128_bytes_consts:
+ .quad 0x0000000000006123 # x^(8*128) mod G(x)
+ .quad 0x0000000000002295 # x^(8*128+64) mod G(x)
+.Lfold_across_64_bytes_consts:
+ .quad 0x0000000000001069 # x^(4*128) mod G(x)
+ .quad 0x000000000000dd31 # x^(4*128+64) mod G(x)
+.Lfold_across_32_bytes_consts:
+ .quad 0x000000000000857d # x^(2*128) mod G(x)
+ .quad 0x0000000000007acc # x^(2*128+64) mod G(x)
+.Lfold_across_16_bytes_consts:
+ .quad 0x000000000000a010 # x^(1*128) mod G(x)
+ .quad 0x0000000000001faa # x^(1*128+64) mod G(x)
+.Lfinal_fold_consts:
+ .quad 0x1368000000000000 # x^48 * (x^48 mod G(x))
+ .quad 0x2d56000000000000 # x^48 * (x^80 mod G(x))
+.Lbarrett_reduction_consts:
+ .quad 0x0000000000018bb7 # G(x)
+ .quad 0x00000001f65a57f8 # floor(x^48 / G(x))
.section .rodata.cst16.mask1, "aM", @progbits, 16
.align 16
-mask1:
-.octa 0x80808080808080808080808080808080
+.Lmask1:
+ .octa 0x80808080808080808080808080808080
.section .rodata.cst16.mask2, "aM", @progbits, 16
.align 16
-mask2:
-.octa 0x00000000FFFFFFFFFFFFFFFFFFFFFFFF
+.Lmask2:
+ .octa 0x00000000FFFFFFFFFFFFFFFFFFFFFFFF
+
+.section .rodata.cst16.bswap_mask, "aM", @progbits, 16
+.align 16
+.Lbswap_mask:
+ .octa 0x000102030405060708090A0B0C0D0E0F
-.section .rodata.cst16.SHUF_MASK, "aM", @progbits, 16
+.section .rodata.cst32.byteshift_table, "aM", @progbits, 32
.align 16
-SHUF_MASK:
-.octa 0x000102030405060708090A0B0C0D0E0F
-
-.section .rodata.cst32.pshufb_shf_table, "aM", @progbits, 32
-.align 32
-pshufb_shf_table:
-# use these values for shift constants for the pshufb instruction
-# different alignments result in values as shown:
-# DDQ 0x008f8e8d8c8b8a898887868584838281 # shl 15 (16-1) / shr1
-# DDQ 0x01008f8e8d8c8b8a8988878685848382 # shl 14 (16-3) / shr2
-# DDQ 0x0201008f8e8d8c8b8a89888786858483 # shl 13 (16-4) / shr3
-# DDQ 0x030201008f8e8d8c8b8a898887868584 # shl 12 (16-4) / shr4
-# DDQ 0x04030201008f8e8d8c8b8a8988878685 # shl 11 (16-5) / shr5
-# DDQ 0x0504030201008f8e8d8c8b8a89888786 # shl 10 (16-6) / shr6
-# DDQ 0x060504030201008f8e8d8c8b8a898887 # shl 9 (16-7) / shr7
-# DDQ 0x07060504030201008f8e8d8c8b8a8988 # shl 8 (16-8) / shr8
-# DDQ 0x0807060504030201008f8e8d8c8b8a89 # shl 7 (16-9) / shr9
-# DDQ 0x090807060504030201008f8e8d8c8b8a # shl 6 (16-10) / shr10
-# DDQ 0x0a090807060504030201008f8e8d8c8b # shl 5 (16-11) / shr11
-# DDQ 0x0b0a090807060504030201008f8e8d8c # shl 4 (16-12) / shr12
-# DDQ 0x0c0b0a090807060504030201008f8e8d # shl 3 (16-13) / shr13
-# DDQ 0x0d0c0b0a090807060504030201008f8e # shl 2 (16-14) / shr14
-# DDQ 0x0e0d0c0b0a090807060504030201008f # shl 1 (16-15) / shr15
-.octa 0x8f8e8d8c8b8a89888786858483828100
-.octa 0x000e0d0c0b0a09080706050403020100
+# For 1 <= len <= 15, the 16-byte vector beginning at &byteshift_table[16 - len]
+# is the index vector to shift left by 'len' bytes, and is also {0x80, ...,
+# 0x80} XOR the index vector to shift right by '16 - len' bytes.
+.Lbyteshift_table:
+ .byte 0x0, 0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87
+ .byte 0x88, 0x89, 0x8a, 0x8b, 0x8c, 0x8d, 0x8e, 0x8f
+ .byte 0x0, 0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7
+ .byte 0x8, 0x9, 0xa, 0xb, 0xc, 0xd, 0xe , 0x0
projects / linux-2.6-block.git / commitdiff