muldi3_hard.S revision 1.1.1.3
1 ###################################- 2 # 3 # Copyright (C) 2009-2016 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 # muldi3_hard.S 27 # 28 # Multiply operation for 64 bit integers, for devices with hard multiply 29 # Input : Operand1[H] in Reg r5 30 # Operand1[L] in Reg r6 31 # Operand2[H] in Reg r7 32 # Operand2[L] in Reg r8 33 # Output: Result[H] in Reg r3 34 # Result[L] in Reg r4 35 # 36 # Explaination: 37 # 38 # Both the input numbers are divided into 16 bit number as follows 39 # op1 = A B C D 40 # op2 = E F G H 41 # result = D * H 42 # + (C * H + D * G) << 16 43 # + (B * H + C * G + D * F) << 32 44 # + (A * H + B * G + C * F + D * E) << 48 45 # 46 # Only 64 bits of the output are considered 47 # 48 ####################################### 49 50 .globl muldi3_hardproc 51 .ent muldi3_hardproc 52 muldi3_hardproc: 53 addi r1,r1,-40 54 55 # Save the input operands on the caller's stack 56 swi r5,r1,44 57 swi r6,r1,48 58 swi r7,r1,52 59 swi r8,r1,56 60 61 # Store all the callee saved registers 62 sw r20,r1,r0 63 swi r21,r1,4 64 swi r22,r1,8 65 swi r23,r1,12 66 swi r24,r1,16 67 swi r25,r1,20 68 swi r26,r1,24 69 swi r27,r1,28 70 71 # Load all the 16 bit values for A through H 72 lhui r20,r1,44 # A 73 lhui r21,r1,46 # B 74 lhui r22,r1,48 # C 75 lhui r23,r1,50 # D 76 lhui r24,r1,52 # E 77 lhui r25,r1,54 # F 78 lhui r26,r1,56 # G 79 lhui r27,r1,58 # H 80 81 # D * H ==> LSB of the result on stack ==> Store1 82 mul r9,r23,r27 83 swi r9,r1,36 # Pos2 and Pos3 84 85 # Hi (Store1) + C * H + D * G ==> Store2 ==> Pos1 and Pos2 86 # Store the carry generated in position 2 for Pos 3 87 lhui r11,r1,36 # Pos2 88 mul r9,r22,r27 # C * H 89 mul r10,r23,r26 # D * G 90 add r9,r9,r10 91 addc r12,r0,r0 92 add r9,r9,r11 93 addc r12,r12,r0 # Store the Carry 94 shi r9,r1,36 # Store Pos2 95 swi r9,r1,32 96 lhui r11,r1,32 97 shi r11,r1,34 # Store Pos1 98 99 # Hi (Store2) + B * H + C * G + D * F ==> Store3 ==> Pos0 and Pos1 100 mul r9,r21,r27 # B * H 101 mul r10,r22,r26 # C * G 102 mul r7,r23,r25 # D * F 103 add r9,r9,r11 104 add r9,r9,r10 105 add r9,r9,r7 106 swi r9,r1,32 # Pos0 and Pos1 107 108 # Hi (Store3) + A * H + B * G + C * F + D * E ==> Store3 ==> Pos0 109 lhui r11,r1,32 # Pos0 110 mul r9,r20,r27 # A * H 111 mul r10,r21,r26 # B * G 112 mul r7,r22,r25 # C * F 113 mul r8,r23,r24 # D * E 114 add r9,r9,r11 115 add r9,r9,r10 116 add r9,r9,r7 117 add r9,r9,r8 118 sext16 r9,r9 # Sign extend the MSB 119 shi r9,r1,32 120 121 # Move results to r3 and r4 122 lhui r3,r1,32 123 add r3,r3,r12 124 shi r3,r1,32 125 lwi r3,r1,32 # Hi Part 126 lwi r4,r1,36 # Lo Part 127 128 # Restore Callee saved registers 129 lw r20,r1,r0 130 lwi r21,r1,4 131 lwi r22,r1,8 132 lwi r23,r1,12 133 lwi r24,r1,16 134 lwi r25,r1,20 135 lwi r26,r1,24 136 lwi r27,r1,28 137 138 # Restore Frame and return 139 rtsd r15,8 140 addi r1,r1,40 141 142 .end muldi3_hardproc 143 144 145
Indexes created Sun Mar 01 05:31:48 UTC 2026