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Copyright 2002 Free Software Foundation, Inc.
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Copyright 2002, 2005 Free Software Foundation, Inc.
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This file is part of the GNU MP Library.
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You should have received a copy of the GNU Lesser General Public License
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along with the GNU MP Library; see the file COPYING.LIB. If not, write to
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the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
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the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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powerpc generic, 604, 604e
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powerpc/750 740, 750, 7400
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================================================
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powerpc generic, 604, 604e, 744x, 745x
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powerpc/750 740, 750, 7400, 7410
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The top-level powerpc directory is currently mostly aimed at 604/604e but
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The code is quite well optimized for the 604e, other chips have had less
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Altivec SIMD available in 7400 might hold some promise, but unfortunately
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Altivec SIMD available in 74xx might hold some promise, but unfortunately
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GMP only guarantees 32-bit data alignment, so there's lots of fiddling
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around with partial operations at the start and end of limb vectors. A
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128-bit limb would be a novel idea, but is unlikely to be practical, since
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it would have to work with ordinary +, -, * etc in the C code.
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Also, Altivec isn't very well suited for the GMP multiplication needs.
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Using floating-point based multiplication has much better better performance
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potential for all current powerpcs, both the ones with slow integer multiply
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units (603, 740, 750, 7400, 7410) and those with fast (604, 604e, 744x,
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745x). This is because all powerpcs do some level of pipelining in the FPU:
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603 and 750 can sustain one fmadd every 2nd cycle.
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604 and 604e can sustain one fmadd per cycle.
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7400 and 7410 can sustain 3 fmadd in 4 cycles.
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744x and 745x can sustain 4 fmadd in 5 cycles.
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The GMP code uses the "r" forms, powerpc-defs.m4 transforms them to plain
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numbers according to what GMP_ASM_POWERPC_R_REGISTERS finds is needed.
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(Note that this style isn't fully general, as the identifier r4 and the
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register r4 will not be distinguishable on some systems. However, this is
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not a problem for the limited GMP assembly usage.)
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lis 9, __gmp_modlimb_invert_table@ha
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rlwinm 11, 5, 31, 25, 31
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la 9, __gmp_modlimb_invert_table@l(9)
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lwz 7, .LCL0-.LCF0(30)
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lwz 11, .LC0-.LCTOC1(30)
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rlwinm 3, 5, 31, 25, 31
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.tc __gmp_modlimb_invert_table[TC],__gmp_modlimb_invert_table[RW]
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rlwinm 0, 5, 31, 25, 31
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lis r2, ha16(___gmp_modlimb_invert_table)
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rlwinm r9, r5, 31, 25, 31
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la r2, lo16(___gmp_modlimb_invert_table)(r2)
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addis r2, r7, ha16(L___gmp_modlimb_invert_table$non_lazy_ptr-L0001$pb)
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rlwinm r9, r5, 31, 25, 31
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lwz r2, lo16(L___gmp_modlimb_invert_table$non_lazy_ptr-L0001$pb)(r2)
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.non_lazy_symbol_pointer
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L___gmp_modlimb_invert_table$non_lazy_ptr:
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.indirect_symbol ___gmp_modlimb_invert_table
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.subsections_via_symbols
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For GNU/Linux and Darwin, we might want to duplicate __gmp_modlimb_invert_table
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into the text section in this file. We should thus be able to reach it like
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rlwinm r9, r5, 31, 25, 31
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addi r9, r9, lo16(local_modlimb_table-L0)
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src/gmp/mpn/powerpc32/README
