root/arch/unicore32/lib/findbit.S

   1 /* SPDX-License-Identifier: GPL-2.0-only */
   2 /*
   3  * linux/arch/unicore32/lib/findbit.S
   4  *
   5  * Code specific to PKUnity SoC and UniCore ISA
   6  *
   7  * Copyright (C) 2001-2010 GUAN Xue-tao
   8  */
   9 #include <linux/linkage.h>
  10 #include <asm/assembler.h>
  11                 .text
  12 
  13 /*
  14  * Purpose  : Find a 'zero' bit
  15  * Prototype: int find_first_zero_bit(void *addr, unsigned int maxbit);
  16  */
  17 ENTRY(find_first_zero_bit)
  18                 cxor.a  r1, #0
  19                 beq     3f
  20                 mov     r2, #0
  21 1:              ldb     r3, [r0+], r2 >> #3
  22                 xor.a   r3, r3, #0xff           @ invert bits
  23                 bne     .L_found                @ any now set - found zero bit
  24                 add     r2, r2, #8              @ next bit pointer
  25 2:              csub.a  r2, r1                  @ any more?
  26                 bub     1b
  27 3:              mov     r0, r1                  @ no free bits
  28                 mov     pc, lr
  29 ENDPROC(find_first_zero_bit)
  30 
  31 /*
  32  * Purpose  : Find next 'zero' bit
  33  * Prototype: int find_next_zero_bit
  34  *              (void *addr, unsigned int maxbit, int offset)
  35  */
  36 ENTRY(find_next_zero_bit)
  37                 cxor.a  r1, #0
  38                 beq     3b
  39                 and.a   ip, r2, #7
  40                 beq     1b                      @ If new byte, goto old routine
  41                 ldb     r3, [r0+], r2 >> #3
  42                 xor     r3, r3, #0xff           @ now looking for a 1 bit
  43                 mov.a   r3, r3 >> ip            @ shift off unused bits
  44                 bne     .L_found
  45                 or      r2, r2, #7              @ if zero, then no bits here
  46                 add     r2, r2, #1              @ align bit pointer
  47                 b       2b                      @ loop for next bit
  48 ENDPROC(find_next_zero_bit)
  49 
  50 /*
  51  * Purpose  : Find a 'one' bit
  52  * Prototype: int find_first_bit
  53  *              (const unsigned long *addr, unsigned int maxbit);
  54  */
  55 ENTRY(find_first_bit)
  56                 cxor.a  r1, #0
  57                 beq     3f
  58                 mov     r2, #0
  59 1:              ldb     r3, [r0+], r2 >> #3
  60                 mov.a   r3, r3
  61                 bne     .L_found                @ any now set - found zero bit
  62                 add     r2, r2, #8              @ next bit pointer
  63 2:              csub.a  r2, r1                  @ any more?
  64                 bub     1b
  65 3:              mov     r0, r1                  @ no free bits
  66                 mov     pc, lr
  67 ENDPROC(find_first_bit)
  68 
  69 /*
  70  * Purpose  : Find next 'one' bit
  71  * Prototype: int find_next_zero_bit
  72  *              (void *addr, unsigned int maxbit, int offset)
  73  */
  74 ENTRY(find_next_bit)
  75                 cxor.a  r1, #0
  76                 beq     3b
  77                 and.a   ip, r2, #7
  78                 beq     1b                      @ If new byte, goto old routine
  79                 ldb     r3, [r0+], r2 >> #3
  80                 mov.a   r3, r3 >> ip            @ shift off unused bits
  81                 bne     .L_found
  82                 or      r2, r2, #7              @ if zero, then no bits here
  83                 add     r2, r2, #1              @ align bit pointer
  84                 b       2b                      @ loop for next bit
  85 ENDPROC(find_next_bit)
  86 
  87 /*
  88  * One or more bits in the LSB of r3 are assumed to be set.
  89  */
  90 .L_found:
  91                 rsub    r1, r3, #0
  92                 and     r3, r3, r1
  93                 cntlz   r3, r3
  94                 rsub    r3, r3, #31
  95                 add     r0, r2, r3
  96                 mov     pc, lr
  97