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darling-xnu/osfmk/arm64/lz4_encode_arm64.s
Thomas A cdbc10b677 Upload xnu-7195.141.2 Source
2023-05-16 21:41:14 -07:00

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/*
* Copyright (c) 2016-2016 Apple Inc. All rights reserved.
*
* @APPLE_OSREFERENCE_LICENSE_HEADER_START@
*
* This file contains Original Code and/or Modifications of Original Code
* as defined in and that are subject to the Apple Public Source License
* Version 2.0 (the 'License'). You may not use this file except in
* compliance with the License. The rights granted to you under the License
* may not be used to create, or enable the creation or redistribution of,
* unlawful or unlicensed copies of an Apple operating system, or to
* circumvent, violate, or enable the circumvention or violation of, any
* terms of an Apple operating system software license agreement.
*
* Please obtain a copy of the License at
* http://www.opensource.apple.com/apsl/ and read it before using this file.
*
* The Original Code and all software distributed under the License are
* distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
* EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
* INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
* Please see the License for the specific language governing rights and
* limitations under the License.
*
* @APPLE_OSREFERENCE_LICENSE_HEADER_END@
*/
#include <vm/lz4_assembly_select.h>
#include <vm/lz4_constants.h>
#include <arm64/asm.h>
#if LZ4_ENABLE_ASSEMBLY_ENCODE_ARM64
/* void lz4_encode_2gb(uint8_t ** dst_ptr,
size_t dst_size,
const uint8_t ** src_ptr,
const uint8_t * src_begin,
size_t src_size,
lz4_hash_entry_t hash_table[LZ4_COMPRESS_HASH_ENTRIES],
int skip_final_literals) */
.globl _lz4_encode_2gb
#define dst_ptr x0
#define dst_size x1
#define src_ptr x2
#define src_begin x3
#define src_size x4
#define hash_table x5
#define skip_final_literals x6
.text
.p2align 4
_lz4_encode_2gb:
// esteblish frame
ARM64_STACK_PROLOG
stp fp, lr, [sp, #-16]!
mov fp, sp
stp x19, x20, [sp, #-16]!
stp x21, x22, [sp, #-16]!
stp x23, x24, [sp, #-16]!
stp x25, x26, [sp, #-16]!
stp x27, x28, [sp, #-16]!
// constant registers
adr x7, L_constant
ldr w28, [x7, #4] // x28 = 0x80808081 (magic number to cmopute 1/255)
ldr w7, [x7] // x7 = LZ4_COMPRESS_HASH_MULTIPLY
mov x27, #-1 // x27 = 0xffffffffffffffff
dup.4s v1, w27 // q1 = {0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff}
// x9 - is current dst
// x10 - dst_end - safety_margin
ldr x9, [x0] // dst
add x10, x9, x1 // dst_end
sub x10, x10, #LZ4_GOFAST_SAFETY_MARGIN // dst_end - safety_margin
cmp x10, x9 // if dst_size < safety_margin abort
b.lt L_done
// x11 - is current src
// x12 - is src_end - safety margin
ldr x11, [x2] // src
add x12, x11, x4 // src_end
sub x12, x12, #LZ4_GOFAST_SAFETY_MARGIN // src_end - safety_margin
cmp x12, x11 // if src_size < safety_margin skip to trailing_literals
b.lt L_trailing_literals
// this block search for the next available match
// set match_begin to current src (which is also where last match ended)
L_search_next_available_match:
mov x13, x11 // match_begin = src
sub x14, x13, x3 // match_postion = match_begin - src_begin
// compute hash value for the next 5 "quads"
// hash distance need to be 0 < D < 0x10000
L_hash_match:
ldr x15, [x13] // match_first_4_bytes
umull x20, w7, w15 // match_bytes * LZ4_COMPRESS_HASH_MULTIPLY
lsr w20, w20, #LZ4_COMPRESS_HASH_SHIFT // use LZ4_COMPRESS_HASH_BITS MSbits as index
add x20, x5, x20, lsl #3 // hash_table_entry ptr (hash + 8*index)
ldp w19, w22, [x20] // read entry values (w19 - pos, w22 - 4 bytes at pos)
stp w14, w15, [x20] // write entry values (w14 - current pos, w15 - current 4 bytes)
add x26, x14, #1 // next_match pos
lsr x25, x15, #8 // next_match_first_4_bytes
umull x21, w7, w25 // match_bytes * LZ4_COMPRESS_HASH_MULTIPLY
lsr w21, w21, #LZ4_COMPRESS_HASH_SHIFT // use LZ4_COMPRESS_HASH_BITS MSbits as index
add x21, x5, x21, lsl #3 // hash_table_entry ptr (hash + 8*index)
ldp w23, w24, [x21] // read entry values (w23 - pos, w24 - 4 bytes at pos)
stp w26, w25, [x21] // write entry values (w26 - next pos, w25 - next 4 bytes)
cmp w15, w22
b.ne L_try_next_match_0 // compare the 4 bytes to see if there is a match
sub w19, w14, w19 // x19 - match_dist (current_pos - match_pos)
cmp w19, #0x10000
ccmp w19, #0, #0xf, lo
b.eq L_try_next_match_0 // verify the 0 < dist < 0x10000
b L_found_valid_match
L_try_next_match_0:
add x13, x13, #1
add x14, x14, #1
add x26, x14, #1 // next_match pos
lsr x15, x15, #16 // next_match_first_4_bytes
umull x20, w7, w15 // match_bytes * LZ4_COMPRESS_HASH_MULTIPLY
lsr w20, w20, #LZ4_COMPRESS_HASH_SHIFT // use LZ4_COMPRESS_HASH_BITS MSbits as index
add x20, x5, x20, lsl #3 // hash_table_entry ptr (hash + 8*index)
ldp w21, w22, [x20] // read entry values (w19 - pos, w22 - 4 bytes at pos)
stp w26, w15, [x20] // write entry values (w14 - current pos, w15 - current 4 bytes)
cmp w25, w24
b.ne L_try_next_match_1 // compare the 4 bytes to see if there is a match
sub w19, w14, w23 // x19 - match_dist (current_pos - match_pos)
cmp w19, #0x10000
ccmp w19, #0, #0xf, lo
b.eq L_try_next_match_1 // verify the 0 < dist < 0x10000
b L_found_valid_match
L_try_next_match_1:
add x13, x13, #1
add x14, x14, #1
add x26, x14, #1 // next_match pos
lsr x25, x15, #8 // next_match_first_4_bytes
umull x20, w7, w25 // match_bytes * LZ4_COMPRESS_HASH_MULTIPLY
lsr w20, w20, #LZ4_COMPRESS_HASH_SHIFT // use LZ4_COMPRESS_HASH_BITS MSbits as index
add x20, x5, x20, lsl #3 // hash_table_entry ptr (hash + 8*index)
ldp w23, w24, [x20] // read entry values (w23 - pos, w24 - 4 bytes at pos)
stp w26, w25, [x20] // write entry values (w26 - next pos, w25 - next 4 bytes)
cmp w15, w22
b.ne L_try_next_match_2 // compare the 4 bytes to see if there is a match
sub w19, w14, w21 // x19 - match_dist (current_pos - match_pos)
cmp w19, #0x10000
ccmp w19, #0, #0xf, lo
b.eq L_try_next_match_2 // verify the 0 < dist < 0x10000
b L_found_valid_match
L_try_next_match_2:
add x13, x13, #1
add x14, x14, #1
add x26, x14, #1 // next_match pos
lsr x15, x15, #16 // next_match_first_4_bytes
umull x20, w7, w15 // match_bytes * LZ4_COMPRESS_HASH_MULTIPLY
lsr w20, w20, #LZ4_COMPRESS_HASH_SHIFT // use LZ4_COMPRESS_HASH_BITS MSbits as index
add x20, x5, x20, lsl #3 // hash_table_entry ptr (hash + 8*index)
ldp w21, w22, [x20] // read entry values (w19 - pos, w22 - 4 bytes at pos)
stp w26, w15, [x20] // write entry values (w14 - current pos, w15 - current 4 bytes)
cmp w25, w24
b.ne L_try_next_match_3 // compare the 4 bytes to see if there is a match
sub w19, w14, w23 // x19 - match_dist (current_pos - match_pos)
cmp w19, #0x10000
ccmp w19, #0, #0xf, lo
b.eq L_try_next_match_3 // verify the 0 < dist < 0x10000
b L_found_valid_match
L_try_next_match_3:
add x13, x13, #1
add x14, x14, #1
cmp w15, w22
b.ne L_try_next_matchs // compare the 4 bytes to see if there is a match
sub w19, w14, w21 // x19 - match_dist (current_pos - match_pos)
cmp w19, #0x10000
ccmp w19, #0, #0xf, lo
b.eq L_try_next_matchs // verify the 0 < dist < 0x10000
b L_found_valid_match
// this block exapnd the valid match as much as possible
// first it try to expand the match forward
// next it try to expand the match backword
L_found_valid_match:
add x20, x13, #4 // match_end = match_begin+4 (already confirmd the first 4 bytes)
sub x21, x20, x19 // ref_end = match_end - dist
L_found_valid_match_expand_forward_loop:
ldr x22, [x20], #8 // load match_current_8_bytes (safe to load becasue of safety margin)
ldr x23, [x21], #8 // load ref_current_8_bytes
cmp x22, x23
b.ne L_found_valid_match_expand_forward_partial
cmp x20, x12 // check if match_end reached src_end
b.lo L_found_valid_match_expand_forward_loop
b L_found_valid_match_expand_backward
L_found_valid_match_expand_forward_partial:
sub x20, x20, #8 // revert match_end by 8 and compute actual match of current 8 bytes
eor x22, x22, x23 // compare the bits using xor
rbit x22, x22 // revert the bits to use clz (the none equivalent bytes would have at least 1 set bit)
clz x22, x22 // after the revrse for every equal prefix byte clz would count 8
add x20, x20, x22, lsr #3 // add the actual number of matching bytes is (clz result)>>3
L_found_valid_match_expand_backward:
sub x15, x13, x19 // ref_begin = match_begin - dist
L_found_valid_match_expand_backward_loop:
cmp x13, x11 // check if match_begin reached src (previous match end)
ccmp x15, x3, #0xd, gt // check if ref_begin reached src_begin
b.le L_found_valid_match_emit_match
ldrb w22, [x13, #-1]! // load match_current_8_bytes (safe to load becasue of safety margin)
ldrb w23, [x15, #-1]! // load ref_current_8_bytes
cmp w22, w23
b.eq L_found_valid_match_expand_backward_loop
add x13, x13, #1 // revert x13, last compare didn't match
// this block write the match into dst
// it write the ML token [extra L tokens] [literals] <2byte dist> [extar M tokens]
// it update src & dst positions and progress to L_search_next_available_match
L_found_valid_match_emit_match:
sub x21, x20, x13 // match_length - match_end - match_begin
sub x21, x21, #4 // match_length - 4 (first 4 bytes are guaranteed)
sub x22, x13, x11 // literals_length = match_begin - src // compute
sub x26, x10, x9 // dst_remaining_space = dst_end - dst
sub x26, x26, x22 // dst_remaining_space -= literals_length
subs x26, x26, #3 // dst_remaining_space -= 2_dist_bytes + L/M_token
b.lo L_done // exit if dst isn't sufficent
and x23, x21, #0xf // store M 4 LSbits
add x23, x23, x22, lsl #4 // add L 4 LSbits
add x15, x9, #1 // tmp_dst = dst + 1
cmp x22, #15 // if L >= 15 need to write more L tokens
b.lo L_found_valid_match_copy_literals
orr x23, x23, #0xf0 // update L/M token to be 0xfM
sub x24, x22, #15 // reduce 15 from number_of_literals
sub x26, x26, #1 // check if there is space for the extra L token
b.lo L_done
cmp x24, #255 // check if need to compute number of 255 tokens
b.lo L_found_valid_match_skip_L_255_tokens
umull x25, w24, w28 // x25 - (literals_to_token * 1_DIV_255_magic_number)
lsr x25, x25, #39 // x25 - number_of_255_tokens = (literals_to_token * 1_DIV_255_magic_number)>>39
subs x26, x26, x25 // check if there is sufficent space for the 255_tokens
b.lo L_done
mov x13, #255
umsubl x24, w25, w13, x24 // x24 - value_of_remainder_token = literals_to_token - (number_of_255_tokens*255)
L_found_valid_match_L_255_tokens_loop:
str q1, [x15], #16 // store 16 255 tokens into dst_tmp. safe to store because dst has safety_margin
subs x25, x25, #16 // check if there are any 255 token left after current 16
b.hi L_found_valid_match_L_255_tokens_loop
add x15, x15, x25 // revert tmp_dst if written too many 255 tokens.
L_found_valid_match_skip_L_255_tokens:
strb w24, [x15], #1 // write last L token
L_found_valid_match_copy_literals:
ldr q0, [x11], #16 // load current 16 literals. (safe becasue src_end has safety margin)
str q0, [x15], #16 // store current 16 literals. (safe becasue dst_end has safety margin)
subs x22, x22, #16
b.gt L_found_valid_match_copy_literals
add x15, x15, x22 // revert tmp_dst if written too many literals
strh w19, [x15], #2 // store dist bytes
cmp x21, #15 // if M >= 15 need to write more M tokens
b.lo L_found_valid_match_finish_writing_match
orr x23, x23, #0xf // update L/M token to be 0xLf
sub x24, x21, #15 // reduce 15 from match_length
sub x26, x26, #1 // check if there is space for the extra M token
b.lo L_done
cmp x24, #255 // check if need to compute number of 255 tokens
b.lo L_found_valid_match_skip_M_255_tokens
umull x25, w24, w28 // x25 - (match_length * 1_DIV_255_magic_number)
lsr x25, x25, #39 // x25 - number_of_255_tokens = (match_length * 1_DIV_255_magic_number)>>39
subs x26, x26, x25 // check if there is sufficent space for the 255_tokens
b.lo L_done
mov x13, #255
umsubl x24, w25, w13, x24 // x24 - value_of_remainder_token = literals_to_token - (match_length*255)
L_found_valid_match_M_255_tokens_loop:
str q1, [x15], #16 // store 16 255 tokens into dst_tmp. safe to store because dst has safety_margin
subs x25, x25, #16 // check if there are any 255 token left after current 16
b.hi L_found_valid_match_M_255_tokens_loop
add x15, x15, x25 // revert tmp_dst if written too many 255 tokens.
L_found_valid_match_skip_M_255_tokens:
strb w24, [x15], #1 // write last M token
L_found_valid_match_finish_writing_match:
strb w23, [x9] // store first token of match in dst
mov x9, x15 // update dst to last postion written
mov x11, x20 // update src to match_end (last byte that was encoded)
cmp x11, x12 // check if src reached src_end
ccmp x9, x10, #9, lt // check if dst reached dst_end
b.ge L_trailing_literals
b L_search_next_available_match
// !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
// attempted to hash three quad values from the end of each emited match
// this eneded up being slower and less compression (???)
// this block set match_begin and pos for next hash search and
// compute the hash values for the last 3 bytes of currently emited match
// only need to comute these hash becasue other "quads" were hashed when the original
// data was read.
L_try_next_matchs:
add x13, x13, #1 // move to next match
add x14, x14, #1 // update next match pos
cmp x13, x12 // check match_begin didn't reach src_end
b.lo L_hash_match
L_trailing_literals:
// unless skip_final_literals is set
// write the trailing bytes as literals
// traliing bytes include the whole src (with the safty margin)
// need to verify whole dst (withthe safty margin) has sufficent space
tst x6, x6
b.ne L_done // if skip_final_literals is set skip writing them
add x12, x12, #LZ4_GOFAST_SAFETY_MARGIN // add safety_margin
subs x13, x12, x11 // remaining_src
b.eq L_done // finish if there are 0 trailing literals
add x10, x10, #LZ4_GOFAST_SAFETY_MARGIN // add safety_margin
sub x14, x10, x9 // remaining dst (dst_end - dst)
sub x14, x14, #1 // 1 byte is needed at least to write literals token
subs x14, x14, x13 // finish if dst can't contain all remaining literals + 1 literals token
b.le L_done // (need to verify that it has room for literals tokens
cmp x13, #15
b.lt L_trailing_literals_store_less_than_15_literals
subs x14, x14, #1 // 1-extra byte is needed for literals tokens
b.mi L_done
mov w15, #0xf0
strb w15, [x9], #1 // write literals first token (Important !!! if 255 tokens exist but dst isn't sufficent need to revert dst by 1)
sub x15, x13, #15
cmp x15, #255
b.lo L_trailing_literals_no_255_tokens
umull x19, w15, w28 // x19 - (literals_to_token * 1_DIV_255_magic_number)
lsr x19, x19, #39 // x19 - number_of_255_tokens = (literals_to_token * 1_DIV_255_magic_number)>>39
subs x14, x14, x19
b.mi L_revert_x9_and_done
mov x26, #255
umsubl x15, w26, w19, x15 // x15 - value_of_remainder_token = literals_to_token - (number_of_255_tokens*255)
L_tariling_literals_write_16_255_tokens:
str q1, [x9], #16 // store 16 255 tokens each iteration (this is safe becasue there is space for 15 or more literals + remainder token)
subs x19, x19, #16
b.gt L_tariling_literals_write_16_255_tokens
add x9, x9, x19 // fixes dst to actual number of tokens (x19 might not be a mulitple of 16)
L_trailing_literals_no_255_tokens:
strb w15, [x9], #1 // store remainder_token
lsr x14, x13, #4 // check if there are more than 16 literals left to be written
tst x14, x14
b.eq L_trailing_literals_copy_less_than_16_literals
L_trailing_literals_copy_16_literals:
ldr q0, [x11], #16 // load current_16_literals
str q0, [ x9], #16 // *dst16++ = current_16_literals
subs x14, x14, #1
b.gt L_trailing_literals_copy_16_literals
cmp x11, x12
b.lo L_trailing_literals_copy_less_than_16_literals
b L_done
L_trailing_literals_store_less_than_15_literals:
lsl x14, x13, #4 // literals_only_token is 0xL0 (where L is 4 bits)
strb w14, [x9], #1 // *dst++ = literals_only_token
L_trailing_literals_copy_less_than_16_literals:
ldrb w13, [x11], #1 // load current_literal
strb w13, [ x9], #1 // *dst++ = current_literal
cmp x11, x12
b.lo L_trailing_literals_copy_less_than_16_literals
// this block upadte dst & src pointers and remove frame
L_done:
str x9, [x0]
str x11, [x2]
ldp x27, x28, [sp], #16
ldp x25, x26, [sp], #16
ldp x23, x24, [sp], #16
ldp x21, x22, [sp], #16
ldp x19, x20, [sp], #16
// clear frame
ldp fp, lr, [sp], #16
ARM64_STACK_EPILOG
L_revert_x9_and_done:
sub x9, x9, #1
b L_done
.p2align 2
L_constant:
.long LZ4_COMPRESS_HASH_MULTIPLY
.long 0x80808081
#endif
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