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-rw-r--r--arch/xtensa/lib/divsi3.S75
1 files changed, 75 insertions, 0 deletions
diff --git a/arch/xtensa/lib/divsi3.S b/arch/xtensa/lib/divsi3.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(__divsi3)
+
+ abi_entry_default
+#if XCHAL_HAVE_DIV32
+ quos a2, a2, a3
+#else
+ xor a7, a2, a3 /* sign = dividend ^ divisor */
+ do_abs a6, a2, a4 /* udividend = abs (dividend) */
+ do_abs a3, a3, a4 /* udivisor = abs (divisor) */
+ bltui a3, 2, .Lle_one /* check if udivisor <= 1 */
+ do_nsau a5, a6, a2, a8 /* udividend_shift = nsau (udividend) */
+ do_nsau a4, a3, a2, a8 /* udivisor_shift = nsau (udivisor) */
+ bgeu a5, a4, .Lspecial
+
+ sub a4, a4, a5 /* count = udivisor_shift - udividend_shift */
+ ssl a4
+ sll a3, a3 /* udivisor <<= 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 if udividend >= udivisor */
+.Lreturn:
+ neg a5, a2
+ movltz a2, a5, a7 /* return (sign < 0) ? -quotient : quotient */
+ abi_ret_default
+
+.Lle_one:
+ beqz a3, .Lerror
+ neg a2, a6 /* if udivisor == 1, then return... */
+ movgez a2, a6, a7 /* (sign < 0) ? -udividend : udividend */
+ abi_ret_default
+
+.Lspecial:
+ bltu a6, a3, .Lreturn0 /* if dividend < divisor, return 0 */
+ movi a2, 1
+ movi a4, -1
+ movltz a2, a4, a7 /* else return (sign < 0) ? -1 : 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(__divsi3)
+EXPORT_SYMBOL(__divsi3)