arch/arm/lib/bitops.h

   1
   2 #if __LINUX_ARM_ARCH__ >= 6 && defined(CONFIG_CPU_32v6K)
   3         .macro  bitop, instr
   4         mov     r2, #1
   5         and     r3, r0, #7              @ Get bit offset
   6         add     r1, r1, r0, lsr #3      @ Get byte offset
   7         mov     r3, r2, lsl r3
   8 1:      ldrexb  r2, [r1]
   9         \instr  r2, r2, r3
  10         strexb  r0, r2, [r1]
  11         cmp     r0, #0
  12         bne     1b
  13         mov     pc, lr
  14         .endm
  15
  16         .macro  testop, instr, store
  17         and     r3, r0, #7              @ Get bit offset
  18         mov     r2, #1
  19         add     r1, r1, r0, lsr #3      @ Get byte offset
  20         mov     r3, r2, lsl r3          @ create mask
  21 1:      ldrexb  r2, [r1]
  22         ands    r0, r2, r3              @ save old value of bit
  23         \instr  r2, r2, r3                      @ toggle bit
  24         strexb  ip, r2, [r1]
  25         cmp     ip, #0
  26         bne     1b
  27         cmp     r0, #0
  28         movne   r0, #1
  29 2:      mov     pc, lr
  30         .endm
  31 #else
  32         .macro  bitop, instr
  33         and     r2, r0, #7
  34         mov     r3, #1
  35         mov     r3, r3, lsl r2
  36         save_and_disable_irqs ip
  37         ldrb    r2, [r1, r0, lsr #3]
  38         \instr  r2, r2, r3
  39         strb    r2, [r1, r0, lsr #3]
  40         restore_irqs ip
  41         mov     pc, lr
  42         .endm
  43
  44 /**
  45  * testop - implement a test_and_xxx_bit operation.
  46  * @instr: operational instruction
  47  * @store: store instruction
  48  *
  49  * Note: we can trivially conditionalise the store instruction
  50  * to avoid dirtying the data cache.
  51  */
  52         .macro  testop, instr, store
  53         add     r1, r1, r0, lsr #3
  54         and     r3, r0, #7
  55         mov     r0, #1
  56         save_and_disable_irqs ip
  57         ldrb    r2, [r1]
  58         tst     r2, r0, lsl r3
  59         \instr  r2, r2, r0, lsl r3
  60         \store  r2, [r1]
  61         restore_irqs ip
  62         moveq   r0, #0
  63         mov     pc, lr
  64         .endm
  65 #endif