"Fossies" - the Fresh Open Source Software Archive

Member "gmp-6.2.1/mpn/powerpc32/README" (14 Nov 2020, 5132 Bytes) of package /linux/misc/gmp-6.2.1.tar.xz:


As a special service "Fossies" has tried to format the requested text file into HTML format (style: standard) with prefixed line numbers. Alternatively you can here view or download the uninterpreted source code file.

    1 Copyright 2002, 2005 Free Software Foundation, Inc.
    2 
    3 This file is part of the GNU MP Library.
    4 
    5 The GNU MP Library is free software; you can redistribute it and/or modify
    6 it under the terms of either:
    7 
    8   * the GNU Lesser General Public License as published by the Free
    9     Software Foundation; either version 3 of the License, or (at your
   10     option) any later version.
   11 
   12 or
   13 
   14   * the GNU General Public License as published by the Free Software
   15     Foundation; either version 2 of the License, or (at your option) any
   16     later version.
   17 
   18 or both in parallel, as here.
   19 
   20 The GNU MP Library is distributed in the hope that it will be useful, but
   21 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
   22 or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
   23 for more details.
   24 
   25 You should have received copies of the GNU General Public License and the
   26 GNU Lesser General Public License along with the GNU MP Library.  If not,
   27 see https://www.gnu.org/licenses/.
   28 
   29 
   30 
   31 
   32 
   33                     POWERPC 32-BIT MPN SUBROUTINES
   34 
   35 
   36 This directory contains mpn functions for various 32-bit PowerPC chips.
   37 
   38 
   39 CODE ORGANIZATION
   40 
   41 	directory	  used for
   42 	================================================
   43 	powerpc           generic, 604, 604e, 744x, 745x
   44 	powerpc/750       740, 750, 7400, 7410
   45 
   46 
   47 The top-level powerpc directory is currently mostly aimed at 604/604e but
   48 should be reasonable on all powerpcs.
   49 
   50 
   51 
   52 STATUS
   53 
   54 The code is quite well optimized for the 604e, other chips have had less
   55 attention.
   56 
   57 Altivec SIMD available in 74xx might hold some promise, but unfortunately
   58 GMP only guarantees 32-bit data alignment, so there's lots of fiddling
   59 around with partial operations at the start and end of limb vectors.  A
   60 128-bit limb would be a novel idea, but is unlikely to be practical, since
   61 it would have to work with ordinary +, -, * etc in the C code.
   62 
   63 Also, Altivec isn't very well suited for the GMP multiplication needs.
   64 Using floating-point based multiplication has much better better performance
   65 potential for all current powerpcs, both the ones with slow integer multiply
   66 units (603, 740, 750, 7400, 7410) and those with fast (604, 604e, 744x,
   67 745x).  This is because all powerpcs do some level of pipelining in the FPU:
   68 
   69 603 and 750 can sustain one fmadd every 2nd cycle.
   70 604 and 604e can sustain one fmadd per cycle.
   71 7400 and 7410 can sustain 3 fmadd in 4 cycles.
   72 744x and 745x can sustain 4 fmadd in 5 cycles.
   73 
   74 
   75 
   76 REGISTER NAMES
   77 
   78 The normal powerpc convention is to give registers as plain numbers, like
   79 "mtctr 6", but on Apple MacOS X (powerpc*-*-rhapsody* and
   80 powerpc*-*-darwin*) the assembler demands an "r" like "mtctr r6".  Note
   81 however when register 0 in an instruction means a literal zero the "r" is
   82 omitted, for instance "lwzx r6,0,r7".
   83 
   84 The GMP code uses the "r" forms, powerpc-defs.m4 transforms them to plain
   85 numbers according to what GMP_ASM_POWERPC_R_REGISTERS finds is needed.
   86 (Note that this style isn't fully general, as the identifier r4 and the
   87 register r4 will not be distinguishable on some systems.  However, this is
   88 not a problem for the limited GMP assembly usage.)
   89 
   90 
   91 
   92 GLOBAL REFERENCES
   93 
   94 Linux non-PIC
   95 	lis	9, __gmp_binvert_limb_table@ha
   96 	rlwinm	11, 5, 31, 25, 31
   97 	la	9, __gmp_binvert_limb_table@l(9)
   98 	lbzx	11, 9, 11
   99 
  100 Linux PIC (FIXME)
  101 .LCL0:
  102 	.long .LCTOC1-.LCF0
  103 	bcl	20, 31, .LCF0
  104 .LCF0:
  105 	mflr	30
  106 	lwz	7, .LCL0-.LCF0(30)
  107 	add	30, 7, 30
  108 	lwz	11, .LC0-.LCTOC1(30)
  109 	rlwinm	3, 5, 31, 25, 31
  110 	lbzx	7, 11, 3
  111 
  112 AIX (always PIC)
  113 LC..0:
  114 	.tc __gmp_binvert_limb_table[TC],__gmp_binvert_limb_table[RW]
  115 	lwz	9, LC..0(2)
  116 	rlwinm	0, 5, 31, 25, 31
  117 	lbzx	0, 9, 0
  118 
  119 Darwin (non-PIC)
  120 	lis	r2, ha16(___gmp_binvert_limb_table)
  121 	rlwinm	r9, r5, 31, 25, 31
  122 	la	r2, lo16(___gmp_binvert_limb_table)(r2)
  123 	lbzx	r0, r2, r9
  124 Darwin (PIC)
  125 	mflr	r0
  126 	bcl	20, 31, L0001$pb
  127 L0001$pb:
  128 	mflr	r7
  129 	mtlr	r0
  130 	addis	r2, r7, ha16(L___gmp_binvert_limb_table$non_lazy_ptr-L0001$pb)
  131 	rlwinm	r9, r5, 31, 25, 31
  132 	lwz	r2, lo16(L___gmp_binvert_limb_table$non_lazy_ptr-L0001$pb)(r2)
  133 	lbzx	r0, r2, r9
  134 ------
  135 	.non_lazy_symbol_pointer
  136 L___gmp_binvert_limb_table$non_lazy_ptr:
  137 	.indirect_symbol ___gmp_binvert_limb_table
  138 	.long	0
  139 	.subsections_via_symbols
  140 
  141 
  142 For GNU/Linux and Darwin, we might want to duplicate __gmp_binvert_limb_table
  143 into the text section in this file.  We should thus be able to reach it like
  144 this:
  145 
  146 	blr	L0
  147 L0:	mflr	r2
  148 	rlwinm	r9, r5, 31, 25, 31
  149 	addi	r9, r9, lo16(local_binvert_table-L0)
  150 	lbzx	r0, r2, r9
  151 
  152 
  153 
  154 REFERENCES
  155 
  156 PowerPC Microprocessor Family: The Programming Environments for 32-bit
  157 Microprocessors, IBM document G522-0290-01, 2000.
  158 
  159 PowerPC 604e RISC Microprocessor User's Manual with Supplement for PowerPC
  160 604 Microprocessor, IBM document G552-0330-00, Freescale document
  161 MPC604EUM/AD, 3/1998.
  162 
  163 MPC7410/MPC7400 RISC Microprocessor User's Manual, Freescale document
  164 MPC7400UM/D, rev 1, 11/2002.
  165 
  166 MPC7450 RISC Microprocessor Family Reference Manual, Freescale document
  167 MPC7450UM, rev 5, 1/2005.
  168 
  169 The above are available online from
  170 
  171 	http://www.ibm.com/chips/techlib/techlib.nsf/productfamilies/PowerPC
  172 	http://www.freescale.com/PowerPC
  173 
  174 
  175 
  176 ----------------
  177 Local variables:
  178 mode: text
  179 fill-column: 76
  180 End: