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28 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
31 ; UINT16 crc16_t10dif_by4(
32 ; UINT16 init_crc, //initial CRC value, 16 bits
33 ; const unsigned char *buf, //buffer pointer to calculate CRC on
34 ; UINT64 len //buffer length in bytes (64-bit data)
42 ; Reference paper titled "Fast CRC Computation for Generic Polynomials Using PCLMULQDQ Instruction"
43 ; URL: http://download.intel.com/design/intarch/papers/323102.pdf
46 %include "reg_sizes.asm"
48 %define fetch_dist 1024
54 %ifidn __OUTPUT_FORMAT__, win64
59 %xdefine arg1_low32 ecx
65 %xdefine arg1_low32 edi
69 global crc16_t10dif_by4:function
72 ; adjust the 16-bit initial_crc value, scale it to 32 bits
75 ; After this point, code flow is exactly same as a 32-bit CRC.
76 ; The only difference is before returning eax, we will shift
77 ; it right 16 bits, to scale back to 16 bits.
81 ; push the xmm registers into the stack to maintain
82 movdqa [rsp+16*2],xmm6
83 movdqa [rsp+16*3],xmm7
85 ; check if smaller than 128B
88 ; for sizes less than 128, we can't fold 64B at a time...
92 ; load the initial crc value
93 movd xmm6, arg1_low32 ; initial crc
95 ; crc value does not need to be byte-reflected, but it needs to
96 ; be moved to the high part of the register.
97 ; because data will be byte-reflected and will align with
98 ; initial crc at correct place.
101 movdqa xmm7, [SHUF_MASK]
102 ; receive the initial 64B data, xor the initial crc value
104 movdqu xmm1, [arg2+16]
105 movdqu xmm2, [arg2+32]
106 movdqu xmm3, [arg2+48]
109 ; XOR the initial_crc value
115 movdqa xmm6, [rk3] ;xmm6 has rk3 and rk4
116 ;imm value of pclmulqdq instruction
117 ;will determine which constant to use
118 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
119 ; we subtract 128 instead of 64 to save one instruction from the loop
122 ; at this section of the code, there is 64*x+y (0<=y<64) bytes of
123 ; buffer. The _fold_64_B_loop
124 ; loop will fold 64B at a time until we have 64+y Bytes of buffer
127 ; fold 64B at a time. This section of the code folds 4 xmm
128 ; registers in parallel
131 ; update the buffer pointer
132 add arg2, 64 ; buf += 64;
134 prefetchnta [arg2+fetch_dist+0]
138 pclmulqdq xmm0, xmm6 , 0x11
139 pclmulqdq xmm1, xmm6 , 0x11
141 pclmulqdq xmm4, xmm6, 0x0
142 pclmulqdq xmm5, xmm6, 0x0
147 prefetchnta [arg2+fetch_dist+32]
151 pclmulqdq xmm2, xmm6, 0x11
152 pclmulqdq xmm3, xmm6, 0x11
154 pclmulqdq xmm4, xmm6, 0x0
155 pclmulqdq xmm5, xmm6, 0x0
161 movdqu xmm5, [arg2+16]
167 movdqu xmm4, [arg2+32]
168 movdqu xmm5, [arg2+48]
177 ; check if there is another 64B in the buffer to be able to fold
179 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
183 ; at this point, the buffer pointer is pointing at the last y Bytes of the buffer
184 ; the 64B of folded data is in 4 of the xmm registers: xmm0, xmm1, xmm2, xmm3
187 ; fold the 4 xmm registers to 1 xmm register with different constants
189 movdqa xmm6, [rk1] ;xmm6 has rk1 and rk2
190 ;imm value of pclmulqdq instruction will
191 ;determine which constant to use
194 pclmulqdq xmm0, xmm6, 0x11
195 pclmulqdq xmm4, xmm6, 0x0
200 pclmulqdq xmm1, xmm6, 0x11
201 pclmulqdq xmm4, xmm6, 0x0
206 pclmulqdq xmm2, xmm6, 0x11
207 pclmulqdq xmm4, xmm6, 0x0
212 ; instead of 64, we add 48 to the loop counter to save 1 instruction from the loop
213 ; instead of a cmp instruction, we use the negative flag with the jl instruction
215 jl _final_reduction_for_128
217 ; now we have 16+y bytes left to reduce. 16 Bytes
218 ; is in register xmm3 and the rest is in memory
219 ; we can fold 16 bytes at a time if y>=16
220 ; continue folding 16B at a time
224 pclmulqdq xmm3, xmm6, 0x11
225 pclmulqdq xmm4, xmm6, 0x0
232 ; instead of a cmp instruction, we utilize the flags with the jge instruction
233 ; equivalent of: cmp arg3, 16-16
234 ; check if there is any more 16B in the buffer to be able to fold
235 jge _16B_reduction_loop
237 ;now we have 16+z bytes left to reduce, where 0<= z < 16.
238 ;first, we reduce the data in the xmm3 register
241 _final_reduction_for_128:
242 ; check if any more data to fold. If not, compute the CRC of the final 128 bits
246 ; here we are getting data that is less than 16 bytes.
247 ; since we know that there was data before the pointer,
248 ; we can offset the input pointer before the actual point,
249 ; to receive exactly 16 bytes.
250 ; after that the registers need to be adjusted.
254 movdqu xmm1, [arg2 - 16 + arg3]
257 ; get rid of the extra data that was loaded before
258 ; load the shift constant
259 lea rax, [pshufb_shf_table + 16]
263 ; shift xmm2 to the left by arg3 bytes
266 ; shift xmm3 to the right by 16-arg3 bytes
269 pblendvb xmm1, xmm2 ;xmm0 is implicit
274 pclmulqdq xmm3, xmm6, 0x11
275 pclmulqdq xmm4, xmm6, 0x0
280 ; compute crc of a 128-bit value
281 movdqa xmm6, [rk5] ; rk5 and rk6 in xmm6
285 pclmulqdq xmm3, xmm6, 0x1
295 pclmulqdq xmm3, xmm6, 0x10
300 movdqa xmm6, [rk7] ; rk7 and rk8 in xmm6
302 pclmulqdq xmm3, xmm6, 0x01
304 pclmulqdq xmm3, xmm6, 0x11
311 ; scale the result back to 16 bits
313 movdqa xmm6, [rsp+16*2]
314 movdqa xmm7, [rsp+16*3]
319 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
320 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
321 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
322 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
327 ; check if there is enough buffer to be able to fold 16B at a time
330 movdqa xmm7, [SHUF_MASK]
332 ; if there is, load the constants
333 movdqa xmm6, [rk1] ; rk1 and rk2 in xmm6
335 movd xmm0, arg1_low32 ; get the initial crc value
336 pslldq xmm0, 12 ; align it to its correct place
337 movdqu xmm3, [arg2] ; load the plaintext
338 pshufb xmm3, xmm7 ; byte-reflect the plaintext
342 ; update the buffer pointer
345 ; update the counter. subtract 32 instead of 16 to save one instruction from the loop
348 jmp _16B_reduction_loop
353 ; mov initial crc to the return value. this is necessary for zero-length buffers.
358 movdqa xmm7, [SHUF_MASK]
360 movd xmm0, arg1_low32 ; get the initial crc value
361 pslldq xmm0, 12 ; align it to its correct place
365 jl _less_than_16_left
367 movdqu xmm3, [arg2] ; load the plaintext
368 pshufb xmm3, xmm7 ; byte-reflect the plaintext
369 pxor xmm3, xmm0 ; xor the initial crc value
372 movdqa xmm6, [rk1] ; rk1 and rk2 in xmm6
373 jmp _get_last_two_xmms
378 ; use stack space to load data less than 16 bytes, zero-out the 16B in memory first.
387 ; backup the counter value
430 pxor xmm3, xmm0 ; xor the initial crc value
433 lea rax, [pshufb_shf_table + 16]
445 pxor xmm3, xmm0 ; xor the initial crc value
465 pxor xmm3, xmm0 ; xor the initial crc value
483 pxor xmm3, xmm0 ; xor the initial crc value
496 pxor xmm3, xmm0 ; xor the initial crc value
504 ; precomputed constants
505 ; these constants are precomputed from the poly: 0x8bb70000 (0x8bb7 scaled to 32 bits)
508 ; rk1 = 2^(32*3) mod Q << 32
509 ; rk2 = 2^(32*5) mod Q << 32
510 ; rk3 = 2^(32*15) mod Q << 32
511 ; rk4 = 2^(32*17) mod Q << 32
512 ; rk5 = 2^(32*3) mod Q << 32
513 ; rk6 = 2^(32*2) mod Q << 32
514 ; rk7 = floor(2^64/Q)
517 DQ 0x2d56000000000000
519 DQ 0x06df000000000000
521 DQ 0x044c000000000000
523 DQ 0xe658000000000000
525 DQ 0x2d56000000000000
527 DQ 0x1368000000000000
529 DQ 0x00000001f65a57f8
531 DQ 0x000000018bb70000
533 dq 0x8080808080808080, 0x8080808080808080
535 dq 0xFFFFFFFFFFFFFFFF, 0x00000000FFFFFFFF
538 dq 0x08090A0B0C0D0E0F, 0x0001020304050607
541 ; use these values for shift constants for the pshufb instruction
542 ; different alignments result in values as shown:
543 ; dq 0x8887868584838281, 0x008f8e8d8c8b8a89 ; shl 15 (16-1) / shr1
544 ; dq 0x8988878685848382, 0x01008f8e8d8c8b8a ; shl 14 (16-3) / shr2
545 ; dq 0x8a89888786858483, 0x0201008f8e8d8c8b ; shl 13 (16-4) / shr3
546 ; dq 0x8b8a898887868584, 0x030201008f8e8d8c ; shl 12 (16-4) / shr4
547 ; dq 0x8c8b8a8988878685, 0x04030201008f8e8d ; shl 11 (16-5) / shr5
548 ; dq 0x8d8c8b8a89888786, 0x0504030201008f8e ; shl 10 (16-6) / shr6
549 ; dq 0x8e8d8c8b8a898887, 0x060504030201008f ; shl 9 (16-7) / shr7
550 ; dq 0x8f8e8d8c8b8a8988, 0x0706050403020100 ; shl 8 (16-8) / shr8
551 ; dq 0x008f8e8d8c8b8a89, 0x0807060504030201 ; shl 7 (16-9) / shr9
552 ; dq 0x01008f8e8d8c8b8a, 0x0908070605040302 ; shl 6 (16-10) / shr10
553 ; dq 0x0201008f8e8d8c8b, 0x0a09080706050403 ; shl 5 (16-11) / shr11
554 ; dq 0x030201008f8e8d8c, 0x0b0a090807060504 ; shl 4 (16-12) / shr12
555 ; dq 0x04030201008f8e8d, 0x0c0b0a0908070605 ; shl 3 (16-13) / shr13
556 ; dq 0x0504030201008f8e, 0x0d0c0b0a09080706 ; shl 2 (16-14) / shr14
557 ; dq 0x060504030201008f, 0x0e0d0c0b0a090807 ; shl 1 (16-15) / shr15
558 dq 0x8786858483828100, 0x8f8e8d8c8b8a8988
559 dq 0x0706050403020100, 0x000e0d0c0b0a0908
561 ;;; func core, ver, snum
562 slversion crc16_t10dif_by4, 05, 02, 0016