;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;  Copyright(c) 2011-2016 Intel Corporation All rights reserved.
;
;  Redistribution and use in source and binary forms, with or without
;  modification, are permitted provided that the following conditions
;  are met:
;    * Redistributions of source code must retain the above copyright
;      notice, this list of conditions and the following disclaimer.
;    * Redistributions in binary form must reproduce the above copyright
;      notice, this list of conditions and the following disclaimer in
;      the documentation and/or other materials provided with the
;      distribution.
;    * Neither the name of Intel Corporation nor the names of its
;      contributors may be used to endorse or promote products derived
;      from this software without specific prior written permission.
;
;  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
;  "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
;  LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
;  A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
;  OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
;  SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
;  LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
;  DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
;  THEORY OF 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:
;       uint64_t crc64_iso_norm_by8(
;               uint64_t init_crc, //initial CRC value, 64 bits
;               const unsigned char *buf, //buffer pointer to calculate CRC on
;               uint64_t len //buffer length in bytes (64-bit data)
;       );
;
%include "reg_sizes.asm"

%define	fetch_dist	1024

[bits 64]
default rel

section .text

%ifidn __OUTPUT_FORMAT__, win64
        %xdefine        arg1 rcx
        %xdefine        arg2 rdx
        %xdefine        arg3 r8
%else
        %xdefine        arg1 rdi
        %xdefine        arg2 rsi
        %xdefine        arg3 rdx
%endif

%define TMP 16*0
%ifidn __OUTPUT_FORMAT__, win64
        %define XMM_SAVE 16*2
        %define VARIABLE_OFFSET 16*10+8
%else
        %define VARIABLE_OFFSET 16*2+8
%endif
align 16
mk_global 	crc64_iso_norm_by8, function
crc64_iso_norm_by8:
	endbranch

	not	arg1      ;~init_crc

	sub	rsp,VARIABLE_OFFSET

%ifidn __OUTPUT_FORMAT__, win64
        ; push the xmm registers into the stack to maintain
        movdqa  [rsp + XMM_SAVE + 16*0], xmm6
        movdqa  [rsp + XMM_SAVE + 16*1], xmm7
        movdqa  [rsp + XMM_SAVE + 16*2], xmm8
        movdqa  [rsp + XMM_SAVE + 16*3], xmm9
        movdqa  [rsp + XMM_SAVE + 16*4], xmm10
        movdqa  [rsp + XMM_SAVE + 16*5], xmm11
        movdqa  [rsp + XMM_SAVE + 16*6], xmm12
        movdqa  [rsp + XMM_SAVE + 16*7], xmm13
%endif


	; check if smaller than 256
	cmp	arg3, 256

	; for sizes less than 256, we can't fold 128B at a time...
	jl	_less_than_256


	; load the initial crc value
	movq	xmm10, arg1	; 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	xmm10, 8

	movdqa xmm11, [SHUF_MASK]
	; receive the initial 128B data, xor the initial crc value
	movdqu	xmm0, [arg2+16*0]
	movdqu	xmm1, [arg2+16*1]
	movdqu	xmm2, [arg2+16*2]
	movdqu	xmm3, [arg2+16*3]
	movdqu	xmm4, [arg2+16*4]
	movdqu	xmm5, [arg2+16*5]
	movdqu	xmm6, [arg2+16*6]
	movdqu	xmm7, [arg2+16*7]

	pshufb	xmm0, xmm11
	; XOR the initial_crc value
	pxor	xmm0, xmm10
	pshufb	xmm1, xmm11
	pshufb	xmm2, xmm11
	pshufb	xmm3, xmm11
	pshufb	xmm4, xmm11
	pshufb	xmm5, xmm11
	pshufb	xmm6, xmm11
	pshufb	xmm7, xmm11

	movdqa	xmm10, [rk3]	;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	arg3, 256

	; at this section of the code, there is 128*x+y (0<=y<128) bytes of buffer. The _fold_128_B_loop
	; loop will fold 128B at a time until we have 128+y Bytes of buffer


	; fold 128B at a time. This section of the code folds 8 xmm registers in parallel
_fold_128_B_loop:

	; update the buffer pointer
	add	arg2, 128		;    buf += 128;

	prefetchnta [arg2+fetch_dist+0]
	movdqu	xmm9, [arg2+16*0]
	movdqu	xmm12, [arg2+16*1]
	pshufb	xmm9, xmm11
	pshufb	xmm12, xmm11
	movdqa	xmm8, xmm0
	movdqa	xmm13, xmm1
	pclmulqdq	xmm0, xmm10, 0x0
	pclmulqdq	xmm8, xmm10 , 0x11
	pclmulqdq	xmm1, xmm10, 0x0
	pclmulqdq	xmm13, xmm10 , 0x11
	pxor	xmm0, xmm9
	xorps	xmm0, xmm8
	pxor	xmm1, xmm12
	xorps	xmm1, xmm13

	prefetchnta [arg2+fetch_dist+32]
	movdqu	xmm9, [arg2+16*2]
	movdqu	xmm12, [arg2+16*3]
	pshufb	xmm9, xmm11
	pshufb	xmm12, xmm11
	movdqa	xmm8, xmm2
	movdqa	xmm13, xmm3
	pclmulqdq	xmm2, xmm10, 0x0
	pclmulqdq	xmm8, xmm10 , 0x11
	pclmulqdq	xmm3, xmm10, 0x0
	pclmulqdq	xmm13, xmm10 , 0x11
	pxor	xmm2, xmm9
	xorps	xmm2, xmm8
	pxor	xmm3, xmm12
	xorps	xmm3, xmm13

	prefetchnta [arg2+fetch_dist+64]
	movdqu	xmm9, [arg2+16*4]
	movdqu	xmm12, [arg2+16*5]
	pshufb	xmm9, xmm11
	pshufb	xmm12, xmm11
	movdqa	xmm8, xmm4
	movdqa	xmm13, xmm5
	pclmulqdq	xmm4, xmm10, 0x0
	pclmulqdq	xmm8, xmm10 , 0x11
	pclmulqdq	xmm5, xmm10, 0x0
	pclmulqdq	xmm13, xmm10 , 0x11
	pxor	xmm4, xmm9
	xorps	xmm4, xmm8
	pxor	xmm5, xmm12
	xorps	xmm5, xmm13

	prefetchnta [arg2+fetch_dist+96]
	movdqu	xmm9, [arg2+16*6]
	movdqu	xmm12, [arg2+16*7]
	pshufb	xmm9, xmm11
	pshufb	xmm12, xmm11
	movdqa	xmm8, xmm6
	movdqa	xmm13, xmm7
	pclmulqdq	xmm6, xmm10, 0x0
	pclmulqdq	xmm8, xmm10 , 0x11
	pclmulqdq	xmm7, xmm10, 0x0
	pclmulqdq	xmm13, xmm10 , 0x11
	pxor	xmm6, xmm9
	xorps	xmm6, xmm8
	pxor	xmm7, xmm12
	xorps	xmm7, xmm13

	sub	arg3, 128

	; check if there is another 128B in the buffer to be able to fold
	jge	_fold_128_B_loop
	;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

	add	arg2, 128
        ; at this point, the buffer pointer is pointing at the last y Bytes of the buffer, where 0 <= y < 128
        ; the 128B of folded data is in 8 of the xmm registers: xmm0, xmm1, xmm2, xmm3, xmm4, xmm5, xmm6, xmm7


	; fold the 8 xmm registers to 1 xmm register with different constants

	movdqa	xmm10, [rk9]
	movdqa	xmm8, xmm0
	pclmulqdq	xmm0, xmm10, 0x11
	pclmulqdq	xmm8, xmm10, 0x0
	pxor	xmm7, xmm8
	xorps	xmm7, xmm0

	movdqa	xmm10, [rk11]
	movdqa	xmm8, xmm1
	pclmulqdq	xmm1, xmm10, 0x11
	pclmulqdq	xmm8, xmm10, 0x0
	pxor	xmm7, xmm8
	xorps	xmm7, xmm1

	movdqa	xmm10, [rk13]
	movdqa	xmm8, xmm2
	pclmulqdq	xmm2, xmm10, 0x11
	pclmulqdq	xmm8, xmm10, 0x0
	pxor	xmm7, xmm8
	pxor	xmm7, xmm2

	movdqa	xmm10, [rk15]
	movdqa	xmm8, xmm3
	pclmulqdq	xmm3, xmm10, 0x11
	pclmulqdq	xmm8, xmm10, 0x0
	pxor	xmm7, xmm8
	xorps	xmm7, xmm3

	movdqa	xmm10, [rk17]
	movdqa	xmm8, xmm4
	pclmulqdq	xmm4, xmm10, 0x11
	pclmulqdq	xmm8, xmm10, 0x0
	pxor	xmm7, xmm8
	pxor	xmm7, xmm4

	movdqa	xmm10, [rk19]
	movdqa	xmm8, xmm5
	pclmulqdq	xmm5, xmm10, 0x11
	pclmulqdq	xmm8, xmm10, 0x0
	pxor	xmm7, xmm8
	xorps	xmm7, xmm5

	movdqa	xmm10, [rk1]	;xmm10 has rk1 and rk2

	movdqa	xmm8, xmm6
	pclmulqdq	xmm6, xmm10, 0x11
	pclmulqdq	xmm8, xmm10, 0x0
	pxor	xmm7, xmm8
	pxor	xmm7, xmm6


	; instead of 128, we add 112 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	arg3, 128-16
	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	xmm8, xmm7
	pclmulqdq	xmm7, xmm10, 0x11
	pclmulqdq	xmm8, xmm10, 0x0
	pxor	xmm7, xmm8
	movdqu	xmm0, [arg2]
	pshufb	xmm0, xmm11
	pxor	xmm7, xmm0
	add	arg2, 16
	sub	arg3, 16
	; 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	arg3, 16
	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:
	movdqa	xmm2, xmm7

	movdqu	xmm1, [arg2 - 16 + arg3]
	pshufb	xmm1, xmm11

	; get rid of the extra data that was loaded before
	; load the shift constant
	lea	rax, [pshufb_shf_table + 16]
	sub	rax, arg3
	movdqu	xmm0, [rax]

	; shift xmm2 to the left by arg3 bytes
	pshufb	xmm2, xmm0

	; shift xmm7 to the right by 16-arg3 bytes
	pxor	xmm0, [mask1]
	pshufb	xmm7, xmm0
	pblendvb	xmm1, xmm2	;xmm0 is implicit

	; fold 16 Bytes
	movdqa	xmm2, xmm1
	movdqa	xmm8, xmm7
	pclmulqdq	xmm7, xmm10, 0x11
	pclmulqdq	xmm8, xmm10, 0x0
	pxor	xmm7, xmm8
	pxor	xmm7, xmm2

_128_done:
	; compute crc of a 128-bit value
	movdqa	xmm10, [rk5]	; rk5 and rk6 in xmm10
	movdqa	xmm0, xmm7

	;64b fold
	pclmulqdq	xmm7, xmm10, 0x01	; H*L
	pslldq	xmm0, 8
	pxor	xmm7, xmm0

	;barrett reduction
_barrett:
	movdqa	xmm10, [rk7]	; rk7 and rk8 in xmm10
	movdqa	xmm0, xmm7

	movdqa	xmm1, xmm7
        pand    xmm1, [mask3]
	pclmulqdq	xmm7, xmm10, 0x01
	pxor	xmm7, xmm1

	pclmulqdq	xmm7, xmm10, 0x11
	pxor	xmm7, xmm0
	pextrq	rax, xmm7, 0

_cleanup:
	not     rax
%ifidn __OUTPUT_FORMAT__, win64
        movdqa  xmm6, [rsp + XMM_SAVE + 16*0]
        movdqa  xmm7, [rsp + XMM_SAVE + 16*1]
        movdqa  xmm8, [rsp + XMM_SAVE + 16*2]
        movdqa  xmm9, [rsp + XMM_SAVE + 16*3]
        movdqa  xmm10, [rsp + XMM_SAVE + 16*4]
        movdqa  xmm11, [rsp + XMM_SAVE + 16*5]
        movdqa  xmm12, [rsp + XMM_SAVE + 16*6]
        movdqa  xmm13, [rsp + XMM_SAVE + 16*7]
%endif
	add	rsp, VARIABLE_OFFSET
	ret

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

align 16
_less_than_256:

	; check if there is enough buffer to be able to fold 16B at a time
	cmp	arg3, 32
	jl	_less_than_32
	movdqa xmm11, [SHUF_MASK]

	; if there is, load the constants
	movdqa	xmm10, [rk1]	; rk1 and rk2 in xmm10

	movq	xmm0, arg1	; get the initial crc value
	pslldq	xmm0, 8	; align it to its correct place
	movdqu	xmm7, [arg2]	; load the plaintext
	pshufb	xmm7, xmm11	; byte-reflect the plaintext
	pxor	xmm7, xmm0


	; update the buffer pointer
	add	arg2, 16

	; update the counter. subtract 32 instead of 16 to save one instruction from the loop
	sub	arg3, 32

	jmp	_16B_reduction_loop
align 16
_less_than_32:
	; mov initial crc to the return value. this is necessary for zero-length buffers.
	mov	rax, arg1
	test	arg3, arg3
	je	_cleanup

	movdqa xmm11, [SHUF_MASK]

	movq	xmm0, arg1	; get the initial crc value
	pslldq	xmm0, 8	; align it to its correct place

	cmp	arg3, 16
	je	_exact_16_left
	jl	_less_than_16_left

	movdqu	xmm7, [arg2]	; load the plaintext
	pshufb	xmm7, xmm11	; byte-reflect the plaintext
	pxor	xmm7, xmm0	; xor the initial crc value
	add	arg2, 16
	sub	arg3, 16
	movdqa	xmm10, [rk1]	; 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	r11, rsp
	movdqa	[r11], xmm1

	;	backup the counter value
	mov	r9, arg3
	cmp	arg3, 8
	jl	_less_than_8_left

	; load 8 Bytes
	mov	rax, [arg2]
	mov	[r11], rax
	add	r11, 8
	sub	arg3, 8
	add	arg2, 8
_less_than_8_left:

	cmp	arg3, 4
	jl	_less_than_4_left

	; load 4 Bytes
	mov	eax, [arg2]
	mov	[r11], eax
	add	r11, 4
	sub	arg3, 4
	add	arg2, 4
_less_than_4_left:

	cmp	arg3, 2
	jl	_less_than_2_left

	; load 2 Bytes
	mov	ax, [arg2]
	mov	[r11], ax
	add	r11, 2
	sub	arg3, 2
	add	arg2, 2
_less_than_2_left:
	cmp     arg3, 1
        jl      _zero_left

	; load 1 Byte
	mov	al, [arg2]
	mov	[r11], al
_zero_left:
	movdqa	xmm7, [rsp]
	pshufb	xmm7, xmm11
	pxor	xmm7, xmm0	; xor the initial crc value

	; shl r9, 4
	lea	rax, [pshufb_shf_table + 16]
	sub	rax, r9

	cmp     r9, 8
        jl      _end_1to7

_end_8to15:
	movdqu	xmm0, [rax]
	pxor	xmm0, [mask1]

	pshufb	xmm7, xmm0
	jmp	_128_done

_end_1to7:
	; Right shift (8-length) bytes in XMM
	add	rax, 8
        movdqu  xmm0, [rax]
        pshufb  xmm7,xmm0

        jmp     _barrett
align 16
_exact_16_left:
	movdqu	xmm7, [arg2]
	pshufb	xmm7, xmm11
	pxor	xmm7, xmm0	; xor the initial crc value

	jmp	_128_done

section .data

; precomputed constants
align 16

rk1:
DQ 0x0000000000000145
rk2:
DQ 0x0000000000001db7
rk3:
DQ 0x000100000001001a
rk4:
DQ 0x001b0000001b015e
rk5:
DQ 0x0000000000000145
rk6:
DQ 0x0000000000000000
rk7:
DQ 0x000000000000001b
rk8:
DQ 0x000000000000001b
rk9:
DQ 0x0150145145145015
rk10:
DQ 0x1c71db6db6db71c7
rk11:
DQ 0x0001110110110111
rk12:
DQ 0x001aab1ab1ab1aab
rk13:
DQ 0x0000014445014445
rk14:
DQ 0x00001daab71daab7
rk15:
DQ 0x0000000101000101
rk16:
DQ 0x0000001b1b001b1b
rk17:
DQ 0x0000000001514515
rk18:
DQ 0x000000001c6db6c7
rk19:
DQ 0x0000000000011011
rk20:
DQ 0x00000000001ab1ab

mask1:
dq 0x8080808080808080, 0x8080808080808080
mask2:
dq 0xFFFFFFFFFFFFFFFF, 0x00000000FFFFFFFF
mask3:
dq 0x0000000000000000, 0xFFFFFFFFFFFFFFFF

SHUF_MASK:
dq 0x08090A0B0C0D0E0F, 0x0001020304050607

pshufb_shf_table:
; use these values for shift constants for the pshufb instruction
; different alignments result in values as shown:
;	dq 0x8887868584838281, 0x008f8e8d8c8b8a89 ; shl 15 (16-1) / shr1
;	dq 0x8988878685848382, 0x01008f8e8d8c8b8a ; shl 14 (16-3) / shr2
;	dq 0x8a89888786858483, 0x0201008f8e8d8c8b ; shl 13 (16-4) / shr3
;	dq 0x8b8a898887868584, 0x030201008f8e8d8c ; shl 12 (16-4) / shr4
;	dq 0x8c8b8a8988878685, 0x04030201008f8e8d ; shl 11 (16-5) / shr5
;	dq 0x8d8c8b8a89888786, 0x0504030201008f8e ; shl 10 (16-6) / shr6
;	dq 0x8e8d8c8b8a898887, 0x060504030201008f ; shl 9  (16-7) / shr7
;	dq 0x8f8e8d8c8b8a8988, 0x0706050403020100 ; shl 8  (16-8) / shr8
;	dq 0x008f8e8d8c8b8a89, 0x0807060504030201 ; shl 7  (16-9) / shr9
;	dq 0x01008f8e8d8c8b8a, 0x0908070605040302 ; shl 6  (16-10) / shr10
;	dq 0x0201008f8e8d8c8b, 0x0a09080706050403 ; shl 5  (16-11) / shr11
;	dq 0x030201008f8e8d8c, 0x0b0a090807060504 ; shl 4  (16-12) / shr12
;	dq 0x04030201008f8e8d, 0x0c0b0a0908070605 ; shl 3  (16-13) / shr13
;	dq 0x0504030201008f8e, 0x0d0c0b0a09080706 ; shl 2  (16-14) / shr14
;	dq 0x060504030201008f, 0x0e0d0c0b0a090807 ; shl 1  (16-15) / shr15
dq 0x8786858483828100, 0x8f8e8d8c8b8a8988
dq 0x0706050403020100, 0x0f0e0d0c0b0a0908
dq 0x8080808080808080, 0x0f0e0d0c0b0a0908
dq 0x8080808080808080, 0x8080808080808080