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Diffstat (limited to 'arch/c6x/lib/divremu.S')

-rw-r--r-- | arch/c6x/lib/divremu.S | 87 |

1 files changed, 87 insertions, 0 deletions

diff --git a/arch/c6x/lib/divremu.S b/arch/c6x/lib/divremu.S new file mode 100644 index 00000000000..caa9f23ee16 --- /dev/null +++ b/arch/c6x/lib/divremu.S @@ -0,0 +1,87 @@ +;; Copyright 2011 Free Software Foundation, Inc. +;; Contributed by Bernd Schmidt <bernds@codesourcery.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> + + .text +ENTRY(__c6xabi_divremu) + ;; We use a series of up to 31 subc instructions. First, we find + ;; out how many leading zero bits there are in the divisor. This + ;; gives us both a shift count for aligning (shifting) the divisor + ;; to the, and the number of times we have to execute subc. + + ;; At the end, we have both the remainder and most of the quotient + ;; in A4. The top bit of the quotient is computed first and is + ;; placed in A2. + + ;; Return immediately if the dividend is zero. Setting B4 to 1 + ;; is a trick to allow us to leave the following insns in the jump + ;; delay slot without affecting the result. + mv .s2x A4, B1 + + [b1] lmbd .l2 1, B4, B1 +||[!b1] b .s2 B3 ; RETURN A +||[!b1] mvk .d2 1, B4 + +||[!b1] zero .s1 A5 + mv .l1x B1, A6 +|| shl .s2 B4, B1, B4 + + ;; The loop performs a maximum of 28 steps, so we do the + ;; first 3 here. + cmpltu .l1x A4, B4, A2 + [!A2] sub .l1x A4, B4, A4 +|| shru .s2 B4, 1, B4 +|| xor .s1 1, A2, A2 + + shl .s1 A2, 31, A2 +|| [b1] subc .l1x A4,B4,A4 +|| [b1] add .s2 -1, B1, B1 + [b1] subc .l1x A4,B4,A4 +|| [b1] add .s2 -1, B1, B1 + + ;; RETURN A may happen here (note: must happen before the next branch) +__divremu0: + cmpgt .l2 B1, 7, B0 +|| [b1] subc .l1x A4,B4,A4 +|| [b1] add .s2 -1, B1, B1 + [b1] subc .l1x A4,B4,A4 +|| [b1] add .s2 -1, B1, B1 +|| [b0] b .s1 __divremu0 + [b1] subc .l1x A4,B4,A4 +|| [b1] add .s2 -1, B1, B1 + [b1] subc .l1x A4,B4,A4 +|| [b1] add .s2 -1, B1, B1 + [b1] subc .l1x A4,B4,A4 +|| [b1] add .s2 -1, B1, B1 + [b1] subc .l1x A4,B4,A4 +|| [b1] add .s2 -1, B1, B1 + [b1] subc .l1x A4,B4,A4 +|| [b1] add .s2 -1, B1, B1 + ;; loop backwards branch happens here + + ret .s2 B3 +|| mvk .s1 32, A1 + sub .l1 A1, A6, A6 +|| extu .s1 A4, A6, A5 + shl .s1 A4, A6, A4 + shru .s1 A4, 1, A4 +|| sub .l1 A6, 1, A6 + or .l1 A2, A4, A4 + shru .s1 A4, A6, A4 + nop +ENDPROC(__c6xabi_divremu) |