arch/arm/lib/bitops.h

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