145 lines
3.5 KiB
ArmAsm
145 lines
3.5 KiB
ArmAsm
###################################-
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#
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# Copyright (C) 2009-2013 Free Software Foundation, Inc.
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#
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# Contributed by Michael Eager <eager@eagercon.com>.
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#
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# This file is free software; you can redistribute it and/or modify it
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# under the terms of the GNU General Public License as published by the
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# Free Software Foundation; either version 3, or (at your option) any
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# later version.
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#
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# GCC is distributed in the hope that it will be useful, but WITHOUT
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# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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# or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
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# License for more details.
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#
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# Under Section 7 of GPL version 3, you are granted additional
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# permissions described in the GCC Runtime Library Exception, version
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# 3.1, as published by the Free Software Foundation.
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#
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# You should have received a copy of the GNU General Public License and
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# a copy of the GCC Runtime Library Exception along with this program;
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# see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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# <http://www.gnu.org/licenses/>.
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#
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# muldi3_hard.S
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#
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# Multiply operation for 64 bit integers, for devices with hard multiply
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# Input : Operand1[H] in Reg r5
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# Operand1[L] in Reg r6
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# Operand2[H] in Reg r7
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# Operand2[L] in Reg r8
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# Output: Result[H] in Reg r3
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# Result[L] in Reg r4
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#
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# Explaination:
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#
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# Both the input numbers are divided into 16 bit number as follows
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# op1 = A B C D
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# op2 = E F G H
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# result = D * H
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# + (C * H + D * G) << 16
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# + (B * H + C * G + D * F) << 32
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# + (A * H + B * G + C * F + D * E) << 48
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#
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# Only 64 bits of the output are considered
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#
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#######################################
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.globl muldi3_hardproc
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.ent muldi3_hardproc
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muldi3_hardproc:
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addi r1,r1,-40
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# Save the input operands on the caller's stack
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swi r5,r1,44
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swi r6,r1,48
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swi r7,r1,52
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swi r8,r1,56
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# Store all the callee saved registers
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sw r20,r1,r0
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swi r21,r1,4
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swi r22,r1,8
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swi r23,r1,12
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swi r24,r1,16
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swi r25,r1,20
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swi r26,r1,24
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swi r27,r1,28
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# Load all the 16 bit values for A through H
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lhui r20,r1,44 # A
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lhui r21,r1,46 # B
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lhui r22,r1,48 # C
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lhui r23,r1,50 # D
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lhui r24,r1,52 # E
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lhui r25,r1,54 # F
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lhui r26,r1,56 # G
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lhui r27,r1,58 # H
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# D * H ==> LSB of the result on stack ==> Store1
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mul r9,r23,r27
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swi r9,r1,36 # Pos2 and Pos3
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# Hi (Store1) + C * H + D * G ==> Store2 ==> Pos1 and Pos2
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# Store the carry generated in position 2 for Pos 3
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lhui r11,r1,36 # Pos2
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mul r9,r22,r27 # C * H
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mul r10,r23,r26 # D * G
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add r9,r9,r10
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addc r12,r0,r0
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add r9,r9,r11
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addc r12,r12,r0 # Store the Carry
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shi r9,r1,36 # Store Pos2
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swi r9,r1,32
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lhui r11,r1,32
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shi r11,r1,34 # Store Pos1
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# Hi (Store2) + B * H + C * G + D * F ==> Store3 ==> Pos0 and Pos1
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mul r9,r21,r27 # B * H
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mul r10,r22,r26 # C * G
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mul r7,r23,r25 # D * F
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add r9,r9,r11
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add r9,r9,r10
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add r9,r9,r7
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swi r9,r1,32 # Pos0 and Pos1
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# Hi (Store3) + A * H + B * G + C * F + D * E ==> Store3 ==> Pos0
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lhui r11,r1,32 # Pos0
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mul r9,r20,r27 # A * H
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mul r10,r21,r26 # B * G
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mul r7,r22,r25 # C * F
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mul r8,r23,r24 # D * E
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add r9,r9,r11
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add r9,r9,r10
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add r9,r9,r7
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add r9,r9,r8
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sext16 r9,r9 # Sign extend the MSB
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shi r9,r1,32
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# Move results to r3 and r4
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lhui r3,r1,32
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add r3,r3,r12
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shi r3,r1,32
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lwi r3,r1,32 # Hi Part
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lwi r4,r1,36 # Lo Part
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# Restore Callee saved registers
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lw r20,r1,r0
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lwi r21,r1,4
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lwi r22,r1,8
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lwi r23,r1,12
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lwi r24,r1,16
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lwi r25,r1,20
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lwi r26,r1,24
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lwi r27,r1,28
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# Restore Frame and return
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rtsd r15,8
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addi r1,r1,40
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.end muldi3_hardproc
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