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-rw-r--r--arch/xtensa/lib/udivsi3.S68
1 files changed, 68 insertions, 0 deletions
diff --git a/arch/xtensa/lib/udivsi3.S b/arch/xtensa/lib/udivsi3.S
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+++ b/arch/xtensa/lib/udivsi3.S
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+/* 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)