arch/arm/lib/findbit.S

   1 /*
   2  *  linux/arch/arm/lib/findbit.S
   3  *
   4  *  Copyright (C) 1995-2000 Russell King
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  *
  10  * 16th March 2001 - John Ripley <jripley@sonicblue.com>
  11  *   Fixed so that "size" is an exclusive not an inclusive quantity.
  12  *   All users of these functions expect exclusive sizes, and may
  13  *   also call with zero size.
  14  * Reworked by rmk.
  15  */
  16 #include <linux/linkage.h>
  17 #include <asm/assembler.h>
  18 #include <asm/export.h>
  19                 .text
  20
  21 /*
  22  * Purpose  : Find a 'zero' bit
  23  * Prototype: int find_first_zero_bit(void *addr, unsigned int maxbit);
  24  */
  25 ENTRY(_find_first_zero_bit_le)
  26                 teq     r1, #0
  27                 beq     3f
  28                 mov     r2, #0
  29 1:
  30  ARM(           ldrb    r3, [r0, r2, lsr #3]    )
  31  THUMB(         lsr     r3, r2, #3              )
  32  THUMB(         ldrb    r3, [r0, r3]            )
  33                 eors    r3, r3, #0xff           @ invert bits
  34                 bne     .L_found                @ any now set - found zero bit
  35                 add     r2, r2, #8              @ next bit pointer
  36 2:              cmp     r2, r1                  @ any more?
  37                 blo     1b
  38 3:              mov     r0, r1                  @ no free bits
  39                 ret     lr
  40 ENDPROC(_find_first_zero_bit_le)
  41 EXPORT_SYMBOL(_find_first_zero_bit_le)
  42
  43 /*
  44  * Purpose  : Find next 'zero' bit
  45  * Prototype: int find_next_zero_bit(void *addr, unsigned int maxbit, int offset)
  46  */
  47 ENTRY(_find_next_zero_bit_le)
  48                 teq     r1, #0
  49                 beq     3b
  50                 ands    ip, r2, #7
  51                 beq     1b                      @ If new byte, goto old routine
  52  ARM(           ldrb    r3, [r0, r2, lsr #3]    )
  53  THUMB(         lsr     r3, r2, #3              )
  54  THUMB(         ldrb    r3, [r0, r3]            )
  55                 eor     r3, r3, #0xff           @ now looking for a 1 bit
  56                 movs    r3, r3, lsr ip          @ shift off unused bits
  57                 bne     .L_found
  58                 orr     r2, r2, #7              @ if zero, then no bits here
  59                 add     r2, r2, #1              @ align bit pointer
  60                 b       2b                      @ loop for next bit
  61 ENDPROC(_find_next_zero_bit_le)
  62 EXPORT_SYMBOL(_find_next_zero_bit_le)
  63
  64 /*
  65  * Purpose  : Find a 'one' bit
  66  * Prototype: int find_first_bit(const unsigned long *addr, unsigned int maxbit);
  67  */
  68 ENTRY(_find_first_bit_le)
  69                 teq     r1, #0
  70                 beq     3f
  71                 mov     r2, #0
  72 1:
  73  ARM(           ldrb    r3, [r0, r2, lsr #3]    )
  74  THUMB(         lsr     r3, r2, #3              )
  75  THUMB(         ldrb    r3, [r0, r3]            )
  76                 movs    r3, r3
  77                 bne     .L_found                @ any now set - found zero bit
  78                 add     r2, r2, #8              @ next bit pointer
  79 2:              cmp     r2, r1                  @ any more?
  80                 blo     1b
  81 3:              mov     r0, r1                  @ no free bits
  82                 ret     lr
  83 ENDPROC(_find_first_bit_le)
  84 EXPORT_SYMBOL(_find_first_bit_le)
  85
  86 /*
  87  * Purpose  : Find next 'one' bit
  88  * Prototype: int find_next_zero_bit(void *addr, unsigned int maxbit, int offset)
  89  */
  90 ENTRY(_find_next_bit_le)
  91                 teq     r1, #0
  92                 beq     3b
  93                 ands    ip, r2, #7
  94                 beq     1b                      @ If new byte, goto old routine
  95  ARM(           ldrb    r3, [r0, r2, lsr #3]    )
  96  THUMB(         lsr     r3, r2, #3              )
  97  THUMB(         ldrb    r3, [r0, r3]            )
  98                 movs    r3, r3, lsr ip          @ shift off unused bits
  99                 bne     .L_found
 100                 orr     r2, r2, #7              @ if zero, then no bits here
 101                 add     r2, r2, #1              @ align bit pointer
 102                 b       2b                      @ loop for next bit
 103 ENDPROC(_find_next_bit_le)
 104 EXPORT_SYMBOL(_find_next_bit_le)
 105
 106 #ifdef __ARMEB__
 107
 108 ENTRY(_find_first_zero_bit_be)
 109                 teq     r1, #0
 110                 beq     3f
 111                 mov     r2, #0
 112 1:              eor     r3, r2, #0x18           @ big endian byte ordering
 113  ARM(           ldrb    r3, [r0, r3, lsr #3]    )
 114  THUMB(         lsr     r3, #3                  )
 115  THUMB(         ldrb    r3, [r0, r3]            )
 116                 eors    r3, r3, #0xff           @ invert bits
 117                 bne     .L_found                @ any now set - found zero bit
 118                 add     r2, r2, #8              @ next bit pointer
 119 2:              cmp     r2, r1                  @ any more?
 120                 blo     1b
 121 3:              mov     r0, r1                  @ no free bits
 122                 ret     lr
 123 ENDPROC(_find_first_zero_bit_be)
 124 EXPORT_SYMBOL(_find_first_zero_bit_be)
 125
 126 ENTRY(_find_next_zero_bit_be)
 127                 teq     r1, #0
 128                 beq     3b
 129                 ands    ip, r2, #7
 130                 beq     1b                      @ If new byte, goto old routine
 131                 eor     r3, r2, #0x18           @ big endian byte ordering
 132  ARM(           ldrb    r3, [r0, r3, lsr #3]    )
 133  THUMB(         lsr     r3, #3                  )
 134  THUMB(         ldrb    r3, [r0, r3]            )
 135                 eor     r3, r3, #0xff           @ now looking for a 1 bit
 136                 movs    r3, r3, lsr ip          @ shift off unused bits
 137                 bne     .L_found
 138                 orr     r2, r2, #7              @ if zero, then no bits here
 139                 add     r2, r2, #1              @ align bit pointer
 140                 b       2b                      @ loop for next bit
 141 ENDPROC(_find_next_zero_bit_be)
 142 EXPORT_SYMBOL(_find_next_zero_bit_be)
 143
 144 ENTRY(_find_first_bit_be)
 145                 teq     r1, #0
 146                 beq     3f
 147                 mov     r2, #0
 148 1:              eor     r3, r2, #0x18           @ big endian byte ordering
 149  ARM(           ldrb    r3, [r0, r3, lsr #3]    )
 150  THUMB(         lsr     r3, #3                  )
 151  THUMB(         ldrb    r3, [r0, r3]            )
 152                 movs    r3, r3
 153                 bne     .L_found                @ any now set - found zero bit
 154                 add     r2, r2, #8              @ next bit pointer
 155 2:              cmp     r2, r1                  @ any more?
 156                 blo     1b
 157 3:              mov     r0, r1                  @ no free bits
 158                 ret     lr
 159 ENDPROC(_find_first_bit_be)
 160 EXPORT_SYMBOL(_find_first_bit_be)
 161
 162 ENTRY(_find_next_bit_be)
 163                 teq     r1, #0
 164                 beq     3b
 165                 ands    ip, r2, #7
 166                 beq     1b                      @ If new byte, goto old routine
 167                 eor     r3, r2, #0x18           @ big endian byte ordering
 168  ARM(           ldrb    r3, [r0, r3, lsr #3]    )
 169  THUMB(         lsr     r3, #3                  )
 170  THUMB(         ldrb    r3, [r0, r3]            )
 171                 movs    r3, r3, lsr ip          @ shift off unused bits
 172                 bne     .L_found
 173                 orr     r2, r2, #7              @ if zero, then no bits here
 174                 add     r2, r2, #1              @ align bit pointer
 175                 b       2b                      @ loop for next bit
 176 ENDPROC(_find_next_bit_be)
 177 EXPORT_SYMBOL(_find_next_bit_be)
 178
 179 #endif
 180
 181 /*
 182  * One or more bits in the LSB of r3 are assumed to be set.
 183  */
 184 .L_found:
 185 #if __LINUX_ARM_ARCH__ >= 5
 186                 rsb     r0, r3, #0
 187                 and     r3, r3, r0
 188                 clz     r3, r3
 189                 rsb     r3, r3, #31
 190                 add     r0, r2, r3
 191 #else
 192                 tst     r3, #0x0f
 193                 addeq   r2, r2, #4
 194                 movne   r3, r3, lsl #4
 195                 tst     r3, #0x30
 196                 addeq   r2, r2, #2
 197                 movne   r3, r3, lsl #2
 198                 tst     r3, #0x40
 199                 addeq   r2, r2, #1
 200                 mov     r0, r2
 201 #endif
 202                 cmp     r1, r0                  @ Clamp to maxbit
 203                 movlo   r0, r1
 204                 ret     lr
 205