LXR linux/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
   81:      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        smp_dmb
  221:      ldrexb  r2, [r1]
  23        ands    r0, r2, r3              @ save old value of bit
  24        \instr  r2, r2, r3                      @ toggle bit
  25        strexb  ip, r2, [r1]
  26        cmp     ip, #0
  27        bne     1b
  28        smp_dmb
  29        cmp     r0, #0
  30        movne   r0, #1
  312:      mov     pc, lr
  32        .endm
  33#else
  34        .macro  bitop, instr
  35        and     r2, r0, #7
  36        mov     r3, #1
  37        mov     r3, r3, lsl r2
  38        save_and_disable_irqs ip
  39        ldrb    r2, [r1, r0, lsr #3]
  40        \instr  r2, r2, r3
  41        strb    r2, [r1, r0, lsr #3]
  42        restore_irqs ip
  43        mov     pc, lr
  44        .endm
  45
  46/**
  47 * testop - implement a test_and_xxx_bit operation.
  48 * @instr: operational instruction
  49 * @store: store instruction
  50 *
  51 * Note: we can trivially conditionalise the store instruction
  52 * to avoid dirtying the data cache.
  53 */
  54        .macro  testop, instr, store
  55        add     r1, r1, r0, lsr #3
  56        and     r3, r0, #7
  57        mov     r0, #1
  58        save_and_disable_irqs ip
  59        ldrb    r2, [r1]
  60        tst     r2, r0, lsl r3
  61        \instr  r2, r2, r0, lsl r3
  62        \store  r2, [r1]
  63        moveq   r0, #0
  64        restore_irqs ip
  65        mov     pc, lr
  66        .endm
  67#endif
  68