1###################################
2#
3#  Copyright (C) 2009-2020 Free Software Foundation, Inc.
4#
5#  Contributed by Michael Eager <eager@eagercon.com>.
6#
7#  This file is free software; you can redistribute it and/or modify it
8#  under the terms of the GNU General Public License as published by the
9#  Free Software Foundation; either version 3, or (at your option) any
10#  later version.
11#
12#  GCC is distributed in the hope that it will be useful, but WITHOUT
13#  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
14#  or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public
15#  License for more details.
16#
17#  Under Section 7 of GPL version 3, you are granted additional
18#  permissions described in the GCC Runtime Library Exception, version
19#  3.1, as published by the Free Software Foundation.
20#
21#  You should have received a copy of the GNU General Public License and
22#  a copy of the GCC Runtime Library Exception along with this program;
23#  see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
24#  <http://www.gnu.org/licenses/>.
25#
26#  modsi3.S
27#
28#  modulo operation for 64 bit integers.
29#
30#######################################
31
32
33/* An executable stack is *not* required for these functions.  */
34#ifdef __linux__
35.section .note.GNU-stack,"",%progbits
36.previous
37#endif
38
39	.globl	__moddi3
40	.ent	__moddi3
41__moddi3:
42	.frame	r1,0,r15
43
44#Change the stack pointer value and Save callee saved regs
45	addik	r1,r1,-24
46	swi	r25,r1,0
47	swi	r26,r1,4
48	swi	r27,r1,8	# used for sign
49	swi	r28,r1,12	# used for loop count
50	swi	r29,r1,16	# Used for div value High
51	swi	r30,r1,20	# Used for div value Low
52
53#Check for Zero Value in the divisor/dividend
54	OR	r9,r5,r6			# Check for the op1 being zero
55	BEQID	r9,$LaResult_Is_Zero		# Result is zero
56	OR	r9,r7,r8			# Check for the dividend being zero
57	BEQI	r9,$LaDiv_By_Zero	        # Div_by_Zero   # Division Error
58	BGEId	r5,$La1_Pos
59	XOR	r27,r5,r7			# Get the sign of the result
60	RSUBI	r6,r6,0				# Make dividend positive
61	RSUBIC	r5,r5,0				# Make dividend positive
62$La1_Pos:
63	BGEI	r7,$La2_Pos
64	RSUBI	r8,r8,0				# Make Divisor Positive
65	RSUBIC	r9,r9,0				# Make Divisor Positive
66$La2_Pos:
67	ADDIK	r4,r0,0				# Clear mod low
68	ADDIK	r3,r0,0                	        # Clear mod high
69	ADDIK	r29,r0,0			# clear div high
70	ADDIK	r30,r0,0			# clear div low
71	ADDIK	r28,r0,64			# Initialize the loop count
72   # First part try to find the first '1' in the r5/r6
73$LaDIV1:
74	ADD	r6,r6,r6
75	ADDC	r5,r5,r5			# left shift logical r5
76	BGEID	r5,$LaDIV1
77	ADDIK	r28,r28,-1
78$LaDIV2:
79	ADD	r6,r6,r6
80	ADDC	r5,r5,r5	# left shift logical r5/r6 get the '1' into the Carry
81	ADDC	r4,r4,r4	# Move that bit into the Mod register
82	ADDC	r3,r3,r3	# Move carry into high mod register
83	rsub	r18,r7,r3	# Compare the High Parts of Mod and Divisor
84	bnei	r18,$L_High_EQ
85	rsub	r18,r6,r4	# Compare Low Parts only if Mod[h] == Divisor[h]
86$L_High_EQ:
87	rSUB	r26,r8,r4	# Subtract divisor[L] from Mod[L]
88	rsubc	r25,r7,r3	# Subtract divisor[H] from Mod[H]
89	BLTi	r25,$LaMOD_TOO_SMALL
90	OR	r3,r0,r25	# move r25 to mod [h]
91	OR	r4,r0,r26	# move r26 to mod [l]
92	ADDI	r30,r30,1
93	ADDC	r29,r29,r0
94$LaMOD_TOO_SMALL:
95	ADDIK	r28,r28,-1
96	BEQi	r28,$LaLOOP_END
97	ADD	r30,r30,r30		# Shift in the '1' into div [low]
98	ADDC	r29,r29,r29		# Move the carry generated into high
99	BRI	$LaDIV2   # Div2
100$LaLOOP_END:
101	BGEI	r27,$LaRETURN_HERE
102	rsubi	r30,r30,0
103	rsubc	r29,r29,r0
104	BRI	$LaRETURN_HERE
105$LaDiv_By_Zero:
106$LaResult_Is_Zero:
107	or	r29,r0,r0	# set result to 0 [High]
108	or	r30,r0,r0	# set result to 0 [Low]
109$LaRETURN_HERE:
110# Restore values of CSRs and that of r29 and the divisor and the dividend
111
112	lwi	r25,r1,0
113	lwi	r26,r1,4
114	lwi	r27,r1,8
115	lwi	r28,r1,12
116	lwi	r29,r1,16
117	lwi	r30,r1,20
118	rtsd	r15,8
119	addik r1,r1,24
120        .end __moddi3
121
122