libgcc/config/microblaze/muldi3_hard.asm

   1 ###################################-
   2 #
   3 #  Copyright 2009, 2010 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.asm
  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 thru 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