Orange Pi5 kernel

^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   1) /* SPDX-License-Identifier: GPL-2.0 */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   2) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   3)  * arch/alpha/lib/ev6-memchr.S
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   4)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   5)  * 21264 version contributed by Rick Gorton <rick.gorton@alpha-processor.com>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   6)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   7)  * Finds characters in a memory area.  Optimized for the Alpha:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   8)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   9)  *    - memory accessed as aligned quadwords only
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  10)  *    - uses cmpbge to compare 8 bytes in parallel
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  11)  *    - does binary search to find 0 byte in last
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  12)  *      quadword (HAKMEM needed 12 instructions to
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  13)  *      do this instead of the 9 instructions that
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  14)  *      binary search needs).
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  15)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  16)  * For correctness consider that:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  17)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  18)  *    - only minimum number of quadwords may be accessed
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  19)  *    - the third argument is an unsigned long
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  20)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  21)  * Much of the information about 21264 scheduling/coding comes from:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  22)  *	Compiler Writer's Guide for the Alpha 21264
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  23)  *	abbreviated as 'CWG' in other comments here
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  24)  *	ftp.digital.com/pub/Digital/info/semiconductor/literature/dsc-library.html
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  25)  * Scheduling notation:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  26)  *	E	- either cluster
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  27)  *	U	- upper subcluster; U0 - subcluster U0; U1 - subcluster U1
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  28)  *	L	- lower subcluster; L0 - subcluster L0; L1 - subcluster L1
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  29)  * Try not to change the actual algorithm if possible for consistency.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  30)  */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  31) #include <asm/export.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  32)         .set noreorder
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  33)         .set noat
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  34) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  35) 	.align	4
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  36) 	.globl memchr
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  37) 	.ent memchr
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  38) memchr:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  39) 	.frame $30,0,$26,0
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  40) 	.prologue 0
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  41) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  42) 	# Hack -- if someone passes in (size_t)-1, hoping to just
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  43) 	# search til the end of the address space, we will overflow
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  44) 	# below when we find the address of the last byte.  Given
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  45) 	# that we will never have a 56-bit address space, cropping
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  46) 	# the length is the easiest way to avoid trouble.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  47) 	zap	$18, 0x80, $5	# U : Bound length
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  48) 	beq	$18, $not_found	# U :
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  49)         ldq_u   $1, 0($16)	# L : load first quadword Latency=3
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  50) 	and	$17, 0xff, $17	# E : L L U U : 00000000000000ch
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  51) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  52) 	insbl	$17, 1, $2	# U : 000000000000ch00
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  53) 	cmpult	$18, 9, $4	# E : small (< 1 quad) string?
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  54) 	or	$2, $17, $17	# E : 000000000000chch
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  55)         lda     $3, -1($31)	# E : U L L U
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  56) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  57) 	sll	$17, 16, $2	# U : 00000000chch0000
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  58) 	addq	$16, $5, $5	# E : Max search address
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  59) 	or	$2, $17, $17	# E : 00000000chchchch
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  60) 	sll	$17, 32, $2	# U : U L L U : chchchch00000000
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  61) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  62) 	or	$2, $17, $17	# E : chchchchchchchch
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  63) 	extql	$1, $16, $7	# U : $7 is upper bits
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  64) 	beq	$4, $first_quad	# U :
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  65) 	ldq_u	$6, -1($5)	# L : L U U L : eight or less bytes to search Latency=3
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  66) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  67) 	extqh	$6, $16, $6	# U : 2 cycle stall for $6
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  68) 	mov	$16, $0		# E :
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  69) 	nop			# E :
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  70) 	or	$7, $6, $1	# E : L U L U $1 = quadword starting at $16
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  71) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  72) 	# Deal with the case where at most 8 bytes remain to be searched
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  73) 	# in $1.  E.g.:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  74) 	#	$18 = 6
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  75) 	#	$1 = ????c6c5c4c3c2c1
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  76) $last_quad:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  77) 	negq	$18, $6		# E :
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  78)         xor	$17, $1, $1	# E :
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  79) 	srl	$3, $6, $6	# U : $6 = mask of $18 bits set
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  80)         cmpbge  $31, $1, $2	# E : L U L U
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  81) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  82) 	nop
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  83) 	nop
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  84) 	and	$2, $6, $2	# E :
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  85)         beq     $2, $not_found	# U : U L U L
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  86) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  87) $found_it:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  88) #ifdef CONFIG_ALPHA_EV67
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  89) 	/*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  90) 	 * Since we are guaranteed to have set one of the bits, we don't
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  91) 	 * have to worry about coming back with a 0x40 out of cttz...
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  92) 	 */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  93) 	cttz	$2, $3		# U0 :
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  94) 	addq	$0, $3, $0	# E : All done
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  95) 	nop			# E :
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  96) 	ret			# L0 : L U L U
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  97) #else
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  98) 	/*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  99) 	 * Slow and clunky.  It can probably be improved.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 100) 	 * An exercise left for others.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 101) 	 */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 102)         negq    $2, $3		# E :
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 103)         and     $2, $3, $2	# E :
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 104)         and     $2, 0x0f, $1	# E :
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 105)         addq    $0, 4, $3	# E :
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 106) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 107)         cmoveq  $1, $3, $0	# E : Latency 2, extra map cycle
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 108) 	nop			# E : keep with cmov
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 109)         and     $2, 0x33, $1	# E :
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 110)         addq    $0, 2, $3	# E : U L U L : 2 cycle stall on $0
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 111) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 112)         cmoveq  $1, $3, $0	# E : Latency 2, extra map cycle
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 113) 	nop			# E : keep with cmov
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 114)         and     $2, 0x55, $1	# E :
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 115)         addq    $0, 1, $3	# E : U L U L : 2 cycle stall on $0
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 116) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 117)         cmoveq  $1, $3, $0	# E : Latency 2, extra map cycle
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 118) 	nop
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 119) 	nop
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 120) 	ret			# L0 : L U L U
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 121) #endif
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 122) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 123) 	# Deal with the case where $18 > 8 bytes remain to be
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 124) 	# searched.  $16 may not be aligned.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 125) 	.align 4
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 126) $first_quad:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 127) 	andnot	$16, 0x7, $0	# E :
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 128)         insqh   $3, $16, $2	# U : $2 = 0000ffffffffffff ($16<0:2> ff)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 129)         xor	$1, $17, $1	# E :
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 130) 	or	$1, $2, $1	# E : U L U L $1 = ====ffffffffffff
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 131) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 132)         cmpbge  $31, $1, $2	# E :
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 133)         bne     $2, $found_it	# U :
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 134) 	# At least one byte left to process.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 135) 	ldq	$1, 8($0)	# L :
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 136) 	subq	$5, 1, $18	# E : U L U L
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 137) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 138) 	addq	$0, 8, $0	# E :
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 139) 	# Make $18 point to last quad to be accessed (the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 140) 	# last quad may or may not be partial).
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 141) 	andnot	$18, 0x7, $18	# E :
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 142) 	cmpult	$0, $18, $2	# E :
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 143) 	beq	$2, $final	# U : U L U L
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 144) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 145) 	# At least two quads remain to be accessed.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 146) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 147) 	subq	$18, $0, $4	# E : $4 <- nr quads to be processed
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 148) 	and	$4, 8, $4	# E : odd number of quads?
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 149) 	bne	$4, $odd_quad_count # U :
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 150) 	# At least three quads remain to be accessed
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 151) 	mov	$1, $4		# E : L U L U : move prefetched value to correct reg
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 152) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 153) 	.align	4
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 154) $unrolled_loop:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 155) 	ldq	$1, 8($0)	# L : prefetch $1
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 156) 	xor	$17, $4, $2	# E :
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 157) 	cmpbge	$31, $2, $2	# E :
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 158) 	bne	$2, $found_it	# U : U L U L
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 159) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 160) 	addq	$0, 8, $0	# E :
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 161) 	nop			# E :
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 162) 	nop			# E :
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 163) 	nop			# E :
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 164) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 165) $odd_quad_count:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 166) 	xor	$17, $1, $2	# E :
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 167) 	ldq	$4, 8($0)	# L : prefetch $4
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 168) 	cmpbge	$31, $2, $2	# E :
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 169) 	addq	$0, 8, $6	# E :
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 170) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 171) 	bne	$2, $found_it	# U :
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 172) 	cmpult	$6, $18, $6	# E :
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 173) 	addq	$0, 8, $0	# E :
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 174) 	nop			# E :
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 175) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 176) 	bne	$6, $unrolled_loop # U :
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 177) 	mov	$4, $1		# E : move prefetched value into $1
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 178) 	nop			# E :
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 179) 	nop			# E :
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 180) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 181) $final:	subq	$5, $0, $18	# E : $18 <- number of bytes left to do
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 182) 	nop			# E :
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 183) 	nop			# E :
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 184) 	bne	$18, $last_quad	# U :
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 185) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 186) $not_found:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 187) 	mov	$31, $0		# E :
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 188) 	nop			# E :
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 189) 	nop			# E :
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 190) 	ret			# L0 :
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 191) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 192)         .end memchr
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 193) 	EXPORT_SYMBOL(memchr)