Orange Pi5 kernel

^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  1) /* SPDX-License-Identifier: GPL-2.0-or-later */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  2) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  3)  * Divide a 64-bit unsigned number by a 32-bit unsigned number.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  4)  * This routine assumes that the top 32 bits of the dividend are
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  5)  * non-zero to start with.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  6)  * On entry, r3 points to the dividend, which get overwritten with
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  7)  * the 64-bit quotient, and r4 contains the divisor.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  8)  * On exit, r3 contains the remainder.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  9)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 10)  * Copyright (C) 2002 Paul Mackerras, IBM Corp.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 11)  */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 12) #include <asm/ppc_asm.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 13) #include <asm/processor.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 14) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 15) _GLOBAL(__div64_32)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 16) 	lwz	r5,0(r3)	# get the dividend into r5/r6
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 17) 	lwz	r6,4(r3)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 18) 	cmplw	r5,r4
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 19) 	li	r7,0
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 20) 	li	r8,0
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 21) 	blt	1f
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 22) 	divwu	r7,r5,r4	# if dividend.hi >= divisor,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 23) 	mullw	r0,r7,r4	# quotient.hi = dividend.hi / divisor
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 24) 	subf.	r5,r0,r5	# dividend.hi %= divisor
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 25) 	beq	3f
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 26) 1:	mr	r11,r5		# here dividend.hi != 0
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 27) 	andis.	r0,r5,0xc000
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 28) 	bne	2f
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 29) 	cntlzw	r0,r5		# we are shifting the dividend right
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 30) 	li	r10,-1		# to make it < 2^32, and shifting
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 31) 	srw	r10,r10,r0	# the divisor right the same amount,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 32) 	addc	r9,r4,r10	# rounding up (so the estimate cannot
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 33) 	andc	r11,r6,r10	# ever be too large, only too small)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 34) 	andc	r9,r9,r10
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 35) 	addze	r9,r9
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 36) 	or	r11,r5,r11
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 37) 	rotlw	r9,r9,r0
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 38) 	rotlw	r11,r11,r0
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 39) 	divwu	r11,r11,r9	# then we divide the shifted quantities
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 40) 2:	mullw	r10,r11,r4	# to get an estimate of the quotient,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 41) 	mulhwu	r9,r11,r4	# multiply the estimate by the divisor,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 42) 	subfc	r6,r10,r6	# take the product from the divisor,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 43) 	add	r8,r8,r11	# and add the estimate to the accumulated
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 44) 	subfe.	r5,r9,r5	# quotient
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 45) 	bne	1b
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 46) 3:	cmplw	r6,r4
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 47) 	blt	4f
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 48) 	divwu	r0,r6,r4	# perform the remaining 32-bit division
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 49) 	mullw	r10,r0,r4	# and get the remainder
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 50) 	add	r8,r8,r0
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 51) 	subf	r6,r10,r6
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 52) 4:	stw	r7,0(r3)	# return the quotient in *r3
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 53) 	stw	r8,4(r3)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 54) 	mr	r3,r6		# return the remainder in r3
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 55) 	blr