1 ###################################- 2 # 3 # Copyright (C) 2009-2022 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 /* An executable stack is *not* required for these functions. */ 51 #ifdef __linux__ 52 .section .note.GNU-stack,"",%progbits 53 .previous 54 #endif 55 56 .globl muldi3_hardproc 57 .ent muldi3_hardproc 58 muldi3_hardproc: 59 addi r1,r1,-40 60 61 # Save the input operands on the caller's stack 62 swi r5,r1,44 63 swi r6,r1,48 64 swi r7,r1,52 65 swi r8,r1,56 66 67 # Store all the callee saved registers 68 sw r20,r1,r0 69 swi r21,r1,4 70 swi r22,r1,8 71 swi r23,r1,12 72 swi r24,r1,16 73 swi r25,r1,20 74 swi r26,r1,24 75 swi r27,r1,28 76 77 # Load all the 16 bit values for A through H 78 lhui r20,r1,44 # A 79 lhui r21,r1,46 # B 80 lhui r22,r1,48 # C 81 lhui r23,r1,50 # D 82 lhui r24,r1,52 # E 83 lhui r25,r1,54 # F 84 lhui r26,r1,56 # G 85 lhui r27,r1,58 # H 86 87 # D * H ==> LSB of the result on stack ==> Store1 88 mul r9,r23,r27 89 swi r9,r1,36 # Pos2 and Pos3 90 91 # Hi (Store1) + C * H + D * G ==> Store2 ==> Pos1 and Pos2 92 # Store the carry generated in position 2 for Pos 3 93 lhui r11,r1,36 # Pos2 94 mul r9,r22,r27 # C * H 95 mul r10,r23,r26 # D * G 96 add r9,r9,r10 97 addc r12,r0,r0 98 add r9,r9,r11 99 addc r12,r12,r0 # Store the Carry 100 shi r9,r1,36 # Store Pos2 101 swi r9,r1,32 102 lhui r11,r1,32 103 shi r11,r1,34 # Store Pos1 104 105 # Hi (Store2) + B * H + C * G + D * F ==> Store3 ==> Pos0 and Pos1 106 mul r9,r21,r27 # B * H 107 mul r10,r22,r26 # C * G 108 mul r7,r23,r25 # D * F 109 add r9,r9,r11 110 add r9,r9,r10 111 add r9,r9,r7 112 swi r9,r1,32 # Pos0 and Pos1 113 114 # Hi (Store3) + A * H + B * G + C * F + D * E ==> Store3 ==> Pos0 115 lhui r11,r1,32 # Pos0 116 mul r9,r20,r27 # A * H 117 mul r10,r21,r26 # B * G 118 mul r7,r22,r25 # C * F 119 mul r8,r23,r24 # D * E 120 add r9,r9,r11 121 add r9,r9,r10 122 add r9,r9,r7 123 add r9,r9,r8 124 sext16 r9,r9 # Sign extend the MSB 125 shi r9,r1,32 126 127 # Move results to r3 and r4 128 lhui r3,r1,32 129 add r3,r3,r12 130 shi r3,r1,32 131 lwi r3,r1,32 # Hi Part 132 lwi r4,r1,36 # Lo Part 133 134 # Restore Callee saved registers 135 lw r20,r1,r0 136 lwi r21,r1,4 137 lwi r22,r1,8 138 lwi r23,r1,12 139 lwi r24,r1,16 140 lwi r25,r1,20 141 lwi r26,r1,24 142 lwi r27,r1,28 143 144 # Restore Frame and return 145 rtsd r15,8 146 addi r1,r1,40 147 148 .end muldi3_hardproc 149 150 151
Indexes created Sat Feb 28 05:31:39 UTC 2026