1 ;; SPDX-License-Identifier: GPL-2.0-or-later 2 ;; Copyright 2010 Free Software Foundation, Inc. 3 ;; Contributed by Bernd Schmidt <bernds@codesourcery.com>. 4 ;; 5 6 #include <linux/linkage.h> 7 8 ;; ABI considerations for the divide functions 9 ;; The following registers are call-used: 10 ;; __c6xabi_divi A0,A1,A2,A4,A6,B0,B1,B2,B4,B5 11 ;; __c6xabi_divu A0,A1,A2,A4,A6,B0,B1,B2,B4 12 ;; __c6xabi_remi A1,A2,A4,A5,A6,B0,B1,B2,B4 13 ;; __c6xabi_remu A1,A4,A5,A7,B0,B1,B2,B4 14 ;; 15 ;; In our implementation, divu and remu are leaf functions, 16 ;; while both divi and remi call into divu. 17 ;; A0 is not clobbered by any of the functions. 18 ;; divu does not clobber B2 either, which is taken advantage of 19 ;; in remi. 20 ;; divi uses B5 to hold the original return address during 21 ;; the call to divu. 22 ;; remi uses B2 and A5 to hold the input values during the 23 ;; call to divu. It stores B3 in on the stack. 24 25 26 .text 27 28 ENTRY(__c6xabi_remu) 29 ;; The ABI seems designed to prevent these functions calling each other, 30 ;; so we duplicate most of the divsi3 code here. 31 mv .s2x A4, B1 32 lmbd .l2 1, B4, B1 33 || [!B1] b .s2 B3 ; RETURN A 34 || [!B1] mvk .d2 1, B4 35 36 mv .l1x B1, A7 37 || shl .s2 B4, B1, B4 38 39 cmpltu .l1x A4, B4, A1 40 [!A1] sub .l1x A4, B4, A4 41 shru .s2 B4, 1, B4 42 43 _remu_loop: 44 cmpgt .l2 B1, 7, B0 45 || [B1] subc .l1x A4,B4,A4 46 || [B1] add .s2 -1, B1, B1 47 ;; RETURN A may happen here (note: must happen before the next branch) 48 [B1] subc .l1x A4,B4,A4 49 || [B1] add .s2 -1, B1, B1 50 || [B0] b .s1 _remu_loop 51 [B1] subc .l1x A4,B4,A4 52 || [B1] add .s2 -1, B1, B1 53 [B1] subc .l1x A4,B4,A4 54 || [B1] add .s2 -1, B1, B1 55 [B1] subc .l1x A4,B4,A4 56 || [B1] add .s2 -1, B1, B1 57 [B1] subc .l1x A4,B4,A4 58 || [B1] add .s2 -1, B1, B1 59 [B1] subc .l1x A4,B4,A4 60 || [B1] add .s2 -1, B1, B1 61 ;; loop backwards branch happens here 62 63 ret .s2 B3 64 [B1] subc .l1x A4,B4,A4 65 || [B1] add .s2 -1, B1, B1 66 [B1] subc .l1x A4,B4,A4 67 68 extu .s1 A4, A7, A4 69 nop 2 70 ENDPROC(__c6xabi_remu) 71