linux/arch/xtensa/lib/umodsi3.S
Max Filippov dbf4ed894c xtensa: add helpers for division, remainder and shifts
Don't rely on libgcc presence, build own versions of the helpers with
correct ABI.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
2022-03-09 14:02:40 -08:00

58 lines
1.3 KiB
ArmAsm

/* SPDX-License-Identifier: GPL-2.0-or-later WITH GCC-exception-2.0 */
#include <linux/linkage.h>
#include <asm/asmmacro.h>
#include <asm/core.h>
ENTRY(__umodsi3)
abi_entry_default
#if XCHAL_HAVE_DIV32
remu a2, a2, a3
#else
bltui a3, 2, .Lle_one /* check if the divisor is <= 1 */
do_nsau a5, a2, a6, a7 /* dividend_shift = nsau (dividend) */
do_nsau a4, a3, a6, a7 /* divisor_shift = nsau (divisor) */
bgeu a5, a4, .Lspecial
sub a4, a4, a5 /* count = divisor_shift - dividend_shift */
ssl a4
sll a3, a3 /* divisor <<= count */
/* test-subtract-and-shift loop */
#if XCHAL_HAVE_LOOPS
loopnez a4, .Lloopend
#endif /* XCHAL_HAVE_LOOPS */
.Lloop:
bltu a2, a3, .Lzerobit
sub a2, a2, a3
.Lzerobit:
srli a3, a3, 1
#if !XCHAL_HAVE_LOOPS
addi a4, a4, -1
bnez a4, .Lloop
#endif /* !XCHAL_HAVE_LOOPS */
.Lloopend:
.Lspecial:
bltu a2, a3, .Lreturn
sub a2, a2, a3 /* subtract once more if dividend >= divisor */
.Lreturn:
abi_ret_default
.Lle_one:
bnez a3, .Lreturn0
/* Divide by zero: Use an illegal instruction to force an exception.
The subsequent "DIV0" string can be recognized by the exception
handler to identify the real cause of the exception. */
ill
.ascii "DIV0"
.Lreturn0:
movi a2, 0
#endif /* XCHAL_HAVE_DIV32 */
abi_ret_default
ENDPROC(__umodsi3)