diff options
| author | Max Filippov <jcmvbkbc@gmail.com> | 2021-10-18 14:29:27 +0300 |
|---|---|---|
| committer | Max Filippov <jcmvbkbc@gmail.com> | 2022-03-10 01:02:40 +0300 |
| commit | dbf4ed894c0fd85d421f7b3b9758ce95398d2925 (patch) | |
| tree | be741f6adb095349d4128f0b792a5b5637ab53b5 /arch/xtensa/lib/udivsi3.S | |
| parent | 8c9ab55c0fbdc76cb876140c2dad75a610bb23ef (diff) | |
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>
Diffstat (limited to 'arch/xtensa/lib/udivsi3.S')
| -rw-r--r-- | arch/xtensa/lib/udivsi3.S | 68 |
1 files changed, 68 insertions, 0 deletions
diff --git a/arch/xtensa/lib/udivsi3.S b/arch/xtensa/lib/udivsi3.S new file mode 100644 index 000000000000..d2477e0786cf --- /dev/null +++ b/arch/xtensa/lib/udivsi3.S @@ -0,0 +1,68 @@ +/* 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(__udivsi3) + + abi_entry_default +#if XCHAL_HAVE_DIV32 + quou a2, a2, a3 +#else + bltui a3, 2, .Lle_one /* check if the divisor <= 1 */ + + mov a6, a2 /* keep dividend in a6 */ + do_nsau a5, a6, a2, a7 /* dividend_shift = nsau (dividend) */ + do_nsau a4, a3, a2, 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 */ + movi a2, 0 /* quotient = 0 */ + + /* test-subtract-and-shift loop; one quotient bit on each iteration */ +#if XCHAL_HAVE_LOOPS + loopnez a4, .Lloopend +#endif /* XCHAL_HAVE_LOOPS */ +.Lloop: + bltu a6, a3, .Lzerobit + sub a6, a6, a3 + addi a2, a2, 1 +.Lzerobit: + slli a2, a2, 1 + srli a3, a3, 1 +#if !XCHAL_HAVE_LOOPS + addi a4, a4, -1 + bnez a4, .Lloop +#endif /* !XCHAL_HAVE_LOOPS */ +.Lloopend: + + bltu a6, a3, .Lreturn + addi a2, a2, 1 /* increment quotient if dividend >= divisor */ +.Lreturn: + abi_ret_default + +.Lle_one: + beqz a3, .Lerror /* if divisor == 1, return the dividend */ + abi_ret_default + +.Lspecial: + /* return dividend >= divisor */ + bltu a6, a3, .Lreturn0 + movi a2, 1 + abi_ret_default + +.Lerror: + /* 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(__udivsi3) |