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Diffstat (limited to 'arch/c6x/lib/remu.S')
-rw-r--r-- | arch/c6x/lib/remu.S | 82 |
1 files changed, 82 insertions, 0 deletions
diff --git a/arch/c6x/lib/remu.S b/arch/c6x/lib/remu.S new file mode 100644 index 00000000..3fae7191 --- /dev/null +++ b/arch/c6x/lib/remu.S @@ -0,0 +1,82 @@ +;; Copyright 2010 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> + + ;; ABI considerations for the divide functions + ;; The following registers are call-used: + ;; __c6xabi_divi A0,A1,A2,A4,A6,B0,B1,B2,B4,B5 + ;; __c6xabi_divu A0,A1,A2,A4,A6,B0,B1,B2,B4 + ;; __c6xabi_remi A1,A2,A4,A5,A6,B0,B1,B2,B4 + ;; __c6xabi_remu A1,A4,A5,A7,B0,B1,B2,B4 + ;; + ;; In our implementation, divu and remu are leaf functions, + ;; while both divi and remi call into divu. + ;; A0 is not clobbered by any of the functions. + ;; divu does not clobber B2 either, which is taken advantage of + ;; in remi. + ;; divi uses B5 to hold the original return address during + ;; the call to divu. + ;; remi uses B2 and A5 to hold the input values during the + ;; call to divu. It stores B3 in on the stack. + + + .text + +ENTRY(__c6xabi_remu) + ;; The ABI seems designed to prevent these functions calling each other, + ;; so we duplicate most of the divsi3 code here. + mv .s2x A4, B1 + lmbd .l2 1, B4, B1 +|| [!B1] b .s2 B3 ; RETURN A +|| [!B1] mvk .d2 1, B4 + + mv .l1x B1, A7 +|| shl .s2 B4, B1, B4 + + cmpltu .l1x A4, B4, A1 + [!A1] sub .l1x A4, B4, A4 + shru .s2 B4, 1, B4 + +_remu_loop: + cmpgt .l2 B1, 7, B0 +|| [B1] subc .l1x A4,B4,A4 +|| [B1] add .s2 -1, B1, B1 + ;; RETURN A may happen here (note: must happen before the next branch) + [B1] subc .l1x A4,B4,A4 +|| [B1] add .s2 -1, B1, B1 +|| [B0] b .s1 _remu_loop + [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 + [B1] subc .l1x A4,B4,A4 +|| [B1] add .s2 -1, B1, B1 + [B1] subc .l1x A4,B4,A4 + + extu .s1 A4, A7, A4 + nop 2 +ENDPROC(__c6xabi_remu) |