src/asm.h

   1 #ifndef ASM_H
   2 #define ASM_H
   3
   4 #include "config.h"
   5 #include "types.h"
   6 #include "func_defines.h"
   7
   8 /**
   9  * Finds the first set bit in a bitmap.
  10  *
  11  * @returns Index of the first set bit.
  12  * @returns -1 if no clear bit was found.
  13  * @param   pvBitmap    Pointer to the bitmap.
  14  * @param   cBits       The number of bits in the bitmap. Multiple of 32.
  15  */
  16 DECLINLINE(int) ASMBitFirstSet(volatile void *pvBitmap, uint32_t cBits)
  17 {
  18     if (cBits)
  19     {
  20         int32_t iBit;
  21 # ifdef RT_INLINE_ASM_GNU_STYLE
  22         RTCCUINTREG uEAX, uECX, uEDI;
  23         cBits = RT_ALIGN_32(cBits, 32);
  24         __asm__ __volatile__("repe; scasl\n\t"
  25                              "je    1f\n\t"
  26 #  ifdef RT_ARCH_AMD64
  27                              "lea   -4(%%rdi), %%rdi\n\t"
  28                              "movl  (%%rdi), %%eax\n\t"
  29                              "subq  %5, %%rdi\n\t"
  30 #  else
  31                              "lea   -4(%%edi), %%edi\n\t"
  32                              "movl  (%%edi), %%eax\n\t"
  33                              "subl  %5, %%edi\n\t"
  34 #  endif
  35                              "shll  $3, %%edi\n\t"
  36                              "bsfl  %%eax, %%edx\n\t"
  37                              "addl  %%edi, %%edx\n\t"
  38                              "1:\t\n"
  39                              : "=d" (iBit),
  40                                "=&c" (uECX),
  41                                "=&D" (uEDI),
  42                                "=&a" (uEAX)
  43                              : "0" (0xffffffff),
  44                                "mr" (pvBitmap),
  45                                "1" (cBits >> 5),
  46                                "2" (pvBitmap),
  47                                "3" (0));
  48 # else
  49         cBits = RT_ALIGN_32(cBits, 32);
  50         __asm
  51         {
  52 #  ifdef RT_ARCH_AMD64
  53             mov     rdi, [pvBitmap]
  54             mov     rbx, rdi
  55 #  else
  56             mov     edi, [pvBitmap]
  57             mov     ebx, edi
  58 #  endif
  59             mov     edx, 0ffffffffh
  60             xor     eax, eax
  61             mov     ecx, [cBits]
  62             shr     ecx, 5
  63             repe    scasd
  64             je      done
  65 #  ifdef RT_ARCH_AMD64
  66             lea     rdi, [rdi - 4]
  67             mov     eax, [rdi]
  68             sub     rdi, rbx
  69 #  else
  70             lea     edi, [edi - 4]
  71             mov     eax, [edi]
  72             sub     edi, ebx
  73 #  endif
  74             shl     edi, 3
  75             bsf     edx, eax
  76             add     edx, edi
  77         done:
  78             mov   [iBit], edx
  79         }
  80 # endif
  81         return iBit;
  82     }
  83     return -1;
  84 }
  85
  86 /**
  87  * Gets the content of the CPU timestamp counter register.
  88  *
  89  * @returns TSC.
  90  */
  91 DECLINLINE(uint64_t) ASMReadTSC(void)
  92 {
  93     RTUINT64U u;
  94 # ifdef RT_INLINE_ASM_GNU_STYLE
  95     __asm__ __volatile__ ("rdtsc\n\t" : "=a" (u.s.Lo), "=d" (u.s.Hi));
  96 # else
  97 #  if RT_INLINE_ASM_USES_INTRIN
  98     u.u = __rdtsc();
  99 #  else
 100     __asm
 101     {
 102         rdtsc
 103         mov     [u.s.Lo], eax
 104         mov     [u.s.Hi], edx
 105     }
 106 #  endif
 107 # endif
 108     return u.u;
 109 }
 110
 111 #endif