From 5d8544e2d0075a5f3c9a2cf27152354d54360da1 Mon Sep 17 00:00:00 2001 From: Palmer Dabbelt Date: Mon, 10 Jul 2017 18:03:19 -0700 Subject: RISC-V: Generic library routines and assembly This patch contains code that is more specific to the RISC-V ISA than it is to Linux. It contains string and math operations, C wrappers for various assembly instructions, stack walking code, and uaccess. Signed-off-by: Palmer Dabbelt --- arch/riscv/lib/memset.S | 120 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 120 insertions(+) create mode 100644 arch/riscv/lib/memset.S (limited to 'arch/riscv/lib/memset.S') diff --git a/arch/riscv/lib/memset.S b/arch/riscv/lib/memset.S new file mode 100644 index 000000000000..a790107cf4c9 --- /dev/null +++ b/arch/riscv/lib/memset.S @@ -0,0 +1,120 @@ +/* + * Copyright (C) 2013 Regents of the University of California + * + * 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, version 2. + * + * 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. + */ + + +#include +#include + +/* void *memset(void *, int, size_t) */ +ENTRY(memset) + move t0, a0 /* Preserve return value */ + + /* Defer to byte-oriented fill for small sizes */ + sltiu a3, a2, 16 + bnez a3, 4f + + /* + * Round to nearest XLEN-aligned address + * greater than or equal to start address + */ + addi a3, t0, SZREG-1 + andi a3, a3, ~(SZREG-1) + beq a3, t0, 2f /* Skip if already aligned */ + /* Handle initial misalignment */ + sub a4, a3, t0 +1: + sb a1, 0(t0) + addi t0, t0, 1 + bltu t0, a3, 1b + sub a2, a2, a4 /* Update count */ + +2: /* Duff's device with 32 XLEN stores per iteration */ + /* Broadcast value into all bytes */ + andi a1, a1, 0xff + slli a3, a1, 8 + or a1, a3, a1 + slli a3, a1, 16 + or a1, a3, a1 +#ifdef CONFIG_64BIT + slli a3, a1, 32 + or a1, a3, a1 +#endif + + /* Calculate end address */ + andi a4, a2, ~(SZREG-1) + add a3, t0, a4 + + andi a4, a4, 31*SZREG /* Calculate remainder */ + beqz a4, 3f /* Shortcut if no remainder */ + neg a4, a4 + addi a4, a4, 32*SZREG /* Calculate initial offset */ + + /* Adjust start address with offset */ + sub t0, t0, a4 + + /* Jump into loop body */ + /* Assumes 32-bit instruction lengths */ + la a5, 3f +#ifdef CONFIG_64BIT + srli a4, a4, 1 +#endif + add a5, a5, a4 + jr a5 +3: + REG_S a1, 0(t0) + REG_S a1, SZREG(t0) + REG_S a1, 2*SZREG(t0) + REG_S a1, 3*SZREG(t0) + REG_S a1, 4*SZREG(t0) + REG_S a1, 5*SZREG(t0) + REG_S a1, 6*SZREG(t0) + REG_S a1, 7*SZREG(t0) + REG_S a1, 8*SZREG(t0) + REG_S a1, 9*SZREG(t0) + REG_S a1, 10*SZREG(t0) + REG_S a1, 11*SZREG(t0) + REG_S a1, 12*SZREG(t0) + REG_S a1, 13*SZREG(t0) + REG_S a1, 14*SZREG(t0) + REG_S a1, 15*SZREG(t0) + REG_S a1, 16*SZREG(t0) + REG_S a1, 17*SZREG(t0) + REG_S a1, 18*SZREG(t0) + REG_S a1, 19*SZREG(t0) + REG_S a1, 20*SZREG(t0) + REG_S a1, 21*SZREG(t0) + REG_S a1, 22*SZREG(t0) + REG_S a1, 23*SZREG(t0) + REG_S a1, 24*SZREG(t0) + REG_S a1, 25*SZREG(t0) + REG_S a1, 26*SZREG(t0) + REG_S a1, 27*SZREG(t0) + REG_S a1, 28*SZREG(t0) + REG_S a1, 29*SZREG(t0) + REG_S a1, 30*SZREG(t0) + REG_S a1, 31*SZREG(t0) + addi t0, t0, 32*SZREG + bltu t0, a3, 3b + andi a2, a2, SZREG-1 /* Update count */ + +4: + /* Handle trailing misalignment */ + beqz a2, 6f + add a3, t0, a2 +5: + sb a1, 0(t0) + addi t0, t0, 1 + bltu t0, a3, 5b +6: + ret +END(memset) -- cgit