mpyll.S
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;; Copyright (C) 2010 Texas Instruments Incorporated
;; Contributed by Mark Salter <msalter@redhat.com>.
;;
;; This program is free software; you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation; either version 2 of the License, or
;; (at your option) any later version.
;;
;; This program is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
;; GNU General Public License for more details.
;;
;; You should have received a copy of the GNU General Public License
;; along with this program; if not, write to the Free Software
;; Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
#include <linux/linkage.h>
;; uint64_t __c6xabi_mpyll(uint64_t x, uint64_t y)
;;
;; 64x64 multiply
;; First compute partial results using 32-bit parts of x and y:
;;
;; b63 b32 b31 b0
;; -----------------------------
;; | 1 | 0 |
;; -----------------------------
;;
;; P0 = X0*Y0
;; P1 = X0*Y1 + X1*Y0
;; P2 = X1*Y1
;;
;; result = (P2 << 64) + (P1 << 32) + P0
;;
;; Since the result is also 64-bit, we can skip the P2 term.
.text
ENTRY(__c6xabi_mpyll)
mpy32u .m1x A4,B4,A1:A0 ; X0*Y0
b .s2 B3
|| mpy32u .m2x B5,A4,B1:B0 ; X0*Y1 (don't need upper 32-bits)
|| mpy32u .m1x A5,B4,A3:A2 ; X1*Y0 (don't need upper 32-bits)
nop
nop
mv .s1 A0,A4
add .l1x A2,B0,A5
add .s1 A1,A5,A5
ENDPROC(__c6xabi_mpyll)