arch/arm26/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                 .text
  19
  20 /*
  21  * Purpose  : Find a 'zero' bit
  22  * Prototype: int find_first_zero_bit(void *addr, unsigned int maxbit);
  23  */
  24 ENTRY(_find_first_zero_bit_le)
  25                 teq     r1, #0
  26                 beq     3f
  27                 mov     r2, #0
  28 1:              ldrb    r3, [r0, r2, lsr #3]
  29                 eors    r3, r3, #0xff           @ invert bits
  30                 bne     .found                  @ any now set - found zero bit
  31                 add     r2, r2, #8              @ next bit pointer
  32 2:              cmp     r2, r1                  @ any more?
  33                 blo     1b
  34 3:              mov     r0, r1                  @ no free bits
  35                 RETINSTR(mov,pc,lr)
  36
  37 /*
  38  * Purpose  : Find next 'zero' bit
  39  * Prototype: int find_next_zero_bit(void *addr, unsigned int maxbit, int offset)
  40  */
  41 ENTRY(_find_next_zero_bit_le)
  42                 teq     r1, #0
  43                 beq     2b
  44                 ands    ip, r2, #7
  45                 beq     1b                      @ If new byte, goto old routine
  46                 ldrb    r3, [r0, r2, lsr #3]
  47                 eor     r3, r3, #0xff           @ now looking for a 1 bit
  48                 movs    r3, r3, lsr ip          @ shift off unused bits
  49                 bne     .found
  50                 orr     r2, r2, #7              @ if zero, then no bits here
  51                 add     r2, r2, #1              @ align bit pointer
  52                 b       2b                      @ loop for next bit
  53
  54 /*
  55  * One or more bits in the LSB of r3 are assumed to be set.
  56  */
  57 .found:         tst     r3, #0x0f
  58                 addeq   r2, r2, #4
  59                 movne   r3, r3, lsl #4
  60                 tst     r3, #0x30
  61                 addeq   r2, r2, #2
  62                 movne   r3, r3, lsl #2
  63                 tst     r3, #0x40
  64                 addeq   r2, r2, #1
  65                 mov     r0, r2
  66                 RETINSTR(mov,pc,lr)
  67