src/libcompiler_builtins/compiler-rt/lib/builtins/arm/bswapdi2.S

   1 //===------- bswapdi2 - Implement bswapdi2 --------------------------------===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is dual licensed under the MIT and the University of Illinois Open
   6 // Source Licenses. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9
  10 #include "../assembly.h"
  11
  12         .syntax unified
  13         .text
  14         DEFINE_CODE_STATE
  15
  16 //
  17 // extern uint64_t __bswapdi2(uint64_t);
  18 //
  19 // Reverse all the bytes in a 64-bit integer.
  20 //
  21         .p2align 2
  22 DEFINE_COMPILERRT_FUNCTION(__bswapdi2)
  23 #if __ARM_ARCH < 6
  24     // before armv6 does not have "rev" instruction
  25     // r2 = rev(r0)
  26     eor r2, r0, r0, ror #16
  27     bic r2, r2, #0xff0000
  28     mov r2, r2, lsr #8
  29     eor r2, r2, r0, ror #8
  30     // r0 = rev(r1)
  31     eor r0, r1, r1, ror #16
  32     bic r0, r0, #0xff0000
  33     mov r0, r0, lsr #8
  34     eor r0, r0, r1, ror #8
  35 #else
  36     rev r2, r0  // r2 = rev(r0)
  37     rev r0, r1  // r0 = rev(r1)
  38 #endif
  39     mov r1, r2  // r1 = r2 = rev(r0)
  40     JMP(lr)
  41 END_COMPILERRT_FUNCTION(__bswapdi2)
  42
  43 NO_EXEC_STACK_DIRECTIVE
  44