| 1 | /* Copyright (C) 1996-2022 Free Software Foundation, Inc. |
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| 2 | This file is part of the GNU C Library. |
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| 3 | |
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| 4 | The GNU C Library is free software; you can redistribute it and/or |
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| 5 | modify it under the terms of the GNU Lesser General Public |
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| 6 | License as published by the Free Software Foundation; either |
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| 7 | version 2.1 of the License, or (at your option) any later version. |
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| 8 | |
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| 9 | The GNU C Library is distributed in the hope that it will be useful, |
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| 10 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
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| 11 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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| 12 | Lesser General Public License for more details. |
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| 13 | |
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| 14 | You should have received a copy of the GNU Lesser General Public |
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| 15 | License along with the GNU C Library. If not, see |
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| 16 | <https://www.gnu.org/licenses/>. */ |
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| 17 | |
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| 18 | /* Finds the first bit set in an integer. Optimized for the Alpha |
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| 19 | architecture. */ |
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| 20 | |
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| 21 | #include <sysdep.h> |
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| 22 | |
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| 23 | .set noreorder |
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| 24 | .set noat |
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| 25 | |
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| 26 | |
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| 27 | ENTRY(__ffs) |
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| 28 | #ifdef PROF |
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| 29 | ldgp gp, 0(pv) |
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| 30 | lda AT, _mcount |
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| 31 | jsr AT, (AT), _mcount |
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| 32 | .prologue 1 |
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| 33 | zap $16, 0xF0, $16 |
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| 34 | br $ffsl..ng |
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| 35 | #else |
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| 36 | .prologue 0 |
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| 37 | zap $16, 0xF0, $16 |
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| 38 | # FALLTHRU |
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| 39 | #endif |
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| 40 | END(__ffs) |
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| 41 | |
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| 42 | .align 4 |
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| 43 | ENTRY(ffsl) |
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| 44 | #ifdef PROF |
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| 45 | ldgp gp, 0(pv) |
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| 46 | lda AT, _mcount |
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| 47 | jsr AT, (AT), _mcount |
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| 48 | .prologue 1 |
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| 49 | $ffsl..ng: |
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| 50 | #else |
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| 51 | .prologue 0 |
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| 52 | #endif |
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| 53 | not $16, $1 # e0 : |
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| 54 | ldi $2, -1 # .. e1 : |
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| 55 | cmpbge $1, $2, $3 # e0 : bit N == 1 for byte N == 0 |
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| 56 | clr $0 # .. e1 : |
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| 57 | addq $3, 1, $4 # e0 : |
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| 58 | bic $4, $3, $3 # e1 : bit N == 1 for first byte N != 0 |
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| 59 | and $3, 0xF0, $4 # e0 : |
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| 60 | and $3, 0xCC, $5 # .. e1 : |
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| 61 | and $3, 0xAA, $6 # e0 : |
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| 62 | cmovne $4, 4, $0 # .. e1 : |
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| 63 | cmovne $5, 2, $5 # e0 : |
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| 64 | cmovne $6, 1, $6 # .. e1 : |
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| 65 | addl $0, $5, $0 # e0 : |
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| 66 | addl $0, $6, $0 # e1 : $0 == N |
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| 67 | extbl $16, $0, $1 # e0 : $1 == byte N |
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| 68 | ldi $2, 1 # .. e1 : |
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| 69 | negq $1, $3 # e0 : |
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| 70 | and $3, $1, $3 # e1 : bit N == least bit set of byte N |
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| 71 | and $3, 0xF0, $4 # e0 : |
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| 72 | and $3, 0xCC, $5 # .. e1 : |
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| 73 | and $3, 0xAA, $6 # e0 : |
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| 74 | cmovne $4, 5, $2 # .. e1 : |
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| 75 | cmovne $5, 2, $5 # e0 : |
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| 76 | cmovne $6, 1, $6 # .. e1 : |
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| 77 | s8addl $0, $2, $0 # e0 : mult byte ofs by 8 and sum |
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| 78 | addl $5, $6, $5 # .. e1 : |
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| 79 | addl $0, $5, $0 # e0 : |
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| 80 | nop # .. e1 : |
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| 81 | cmoveq $16, 0, $0 # e0 : trap input == 0 case. |
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| 82 | ret # .. e1 : 18 |
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| 83 | |
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| 84 | END(ffsl) |
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| 85 | |
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| 86 | weak_alias (__ffs, ffs) |
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| 87 | libc_hidden_def (__ffs) |
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| 88 | libc_hidden_builtin_def (ffs) |
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| 89 | weak_extern (ffsl) |
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| 90 | weak_alias (ffsl, ffsll) |
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| 91 | |
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