| ffs.S (137342) | ffs.S (137463) |
|---|---|
| 1/* $NetBSD: ffs.S,v 1.3 2003/04/05 23:27:15 bjh21 Exp $ */ 2/* 3 * Copyright (c) 2001 Christopher Gilbert 4 * All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: --- 15 unchanged lines hidden (view full) --- 24 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 28 * SUCH DAMAGE. 29 */ 30 31#include <machine/asm.h> | 1/* $NetBSD: ffs.S,v 1.3 2003/04/05 23:27:15 bjh21 Exp $ */ 2/* 3 * Copyright (c) 2001 Christopher Gilbert 4 * All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: --- 15 unchanged lines hidden (view full) --- 24 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 28 * SUCH DAMAGE. 29 */ 30 31#include <machine/asm.h> |
| 32__FBSDID("$FreeBSD: head/sys/libkern/arm/ffs.S 137342 2004-11-07 16:53:29Z cognet $"); | 32__FBSDID("$FreeBSD: head/sys/libkern/arm/ffs.S 137463 2004-11-09 16:47:47Z cognet $"); |
| 33 34 35/* 36 * ffs - find first set bit, this algorithm isolates the first set 37 * bit, then multiplies the number by 0x0450fbaf which leaves the top 38 * 6 bits as an index into the table. This algorithm should be a win 39 * over the checking each bit in turn as per the C compiled version. 40 * --- 18 unchanged lines hidden (view full) --- 59 adrne r2, .L_ffs_table 60 orrne r0, r0, r0, lsl #4 /* r0 = X * 0x11 */ 61 orrne r0, r0, r0, lsl #6 /* r0 = X * 0x451 */ 62 rsbne r0, r0, r0, lsl #16 /* r0 = X * 0x0450fbaf */ 63 64 /* now lookup in table indexed on top 6 bits of r0 */ 65 ldrneb r0, [ r2, r0, lsr #26 ] 66 | 33 34 35/* 36 * ffs - find first set bit, this algorithm isolates the first set 37 * bit, then multiplies the number by 0x0450fbaf which leaves the top 38 * 6 bits as an index into the table. This algorithm should be a win 39 * over the checking each bit in turn as per the C compiled version. 40 * --- 18 unchanged lines hidden (view full) --- 59 adrne r2, .L_ffs_table 60 orrne r0, r0, r0, lsl #4 /* r0 = X * 0x11 */ 61 orrne r0, r0, r0, lsl #6 /* r0 = X * 0x451 */ 62 rsbne r0, r0, r0, lsl #16 /* r0 = X * 0x0450fbaf */ 63 64 /* now lookup in table indexed on top 6 bits of r0 */ 65 ldrneb r0, [ r2, r0, lsr #26 ] 66 |
| 67 mov pc, lr | 67 RET |
| 68.text; 69.type .L_ffs_table, _ASM_TYPE_OBJECT; 70.L_ffs_table: 71/* 0 1 2 3 4 5 6 7 */ 72 .byte 0, 1, 2, 13, 3, 7, 0, 14 /* 0- 7 */ 73 .byte 4, 0, 8, 0, 0, 0, 0, 15 /* 8-15 */ 74 .byte 11, 5, 0, 0, 9, 0, 0, 26 /* 16-23 */ 75 .byte 0, 0, 0, 0, 0, 22, 28, 16 /* 24-31 */ 76 .byte 32, 12, 6, 0, 0, 0, 0, 0 /* 32-39 */ 77 .byte 10, 0, 0, 25, 0, 0, 21, 27 /* 40-47 */ 78 .byte 31, 0, 0, 0, 0, 24, 0, 20 /* 48-55 */ 79 .byte 30, 0, 23, 19, 29, 18, 17, 0 /* 56-63 */ 80#else 81 clzne r0, r0 82 rsbne r0, r0, #32 | 68.text; 69.type .L_ffs_table, _ASM_TYPE_OBJECT; 70.L_ffs_table: 71/* 0 1 2 3 4 5 6 7 */ 72 .byte 0, 1, 2, 13, 3, 7, 0, 14 /* 0- 7 */ 73 .byte 4, 0, 8, 0, 0, 0, 0, 15 /* 8-15 */ 74 .byte 11, 5, 0, 0, 9, 0, 0, 26 /* 16-23 */ 75 .byte 0, 0, 0, 0, 0, 22, 28, 16 /* 24-31 */ 76 .byte 32, 12, 6, 0, 0, 0, 0, 0 /* 32-39 */ 77 .byte 10, 0, 0, 25, 0, 0, 21, 27 /* 40-47 */ 78 .byte 31, 0, 0, 0, 0, 24, 0, 20 /* 48-55 */ 79 .byte 30, 0, 23, 19, 29, 18, 17, 0 /* 56-63 */ 80#else 81 clzne r0, r0 82 rsbne r0, r0, #32 |
| 83 mov pc, lr | 83 RET |
| 84#endif | 84#endif |