openpower/sv/bitmanip.mdwn

   1 # bit to byte permute
   2
   3     do j = 0 to 7
   4       do k = 0 to 7
   5          b = VSR[VRB+32].dword[i].byte[k].bit[j]
   6          VSR[VRT+32].dword[i].byte[j].bit[k] = b
   7
   8 # vector bit deposit
   9
  10 vpdepd VRT,VRA,VRB
  11
  12     do while(m < 64)
  13        if VSR[VRB+32].dword[i].bit[63-m]=1 then do
  14           result = VSR[VRA+32].dword[i].bit[63-k]
  15           VSR[VRT+32].dword[i].bit[63-m] = result
  16           k = k + 1
  17        m = m + 1
  18
  19 # vector bit extract
  20
  21 other way round
  22
  23 # single bit set
  24
  25 ```
  26 uint_xlen_t sbset(uint_xlen_t rs1, uint_xlen_t rs2) { int shamt = rs2 & (XLEN - 1);
  27 }
  28 return rs1 | (uint_xlen_t(1) << shamt);
  29 uint_xlen_t sbclr(uint_xlen_t rs1, uint_xlen_t rs2) { int shamt = rs2 & (XLEN - 1);
  30 }
  31 return rs1 & ~(uint_xlen_t(1) << shamt);
  32 uint_xlen_t sbinv(uint_xlen_t rs1, uint_xlen_t rs2) { int shamt = rs2 & (XLEN - 1);
  33 }
  34 return rs1 ^ (uint_xlen_t(1) << shamt);
  35 uint_xlen_t sbext(uint_xlen_t rs1, uint_xlen_t rs2) { int shamt = rs2 & (XLEN - 1);
  36 }
  37 return 1 & (rs1 >> shamt);
  38 ```
  39
  40 # shuffle / unshuffle
  41
  42 ```
  43 uint64_t shuffle64_stage(uint64_t src, uint64_t maskL, uint64_t maskR, int N) { uint64_t x = src & ~(maskL | maskR);
  44 }
  45 x |= ((src << N) & maskL) | ((src >> N) & maskR); return x;
  46 uint64_t shfl64(uint64_t rs1, uint64_t rs2) { uint64_t x = rs1;
  47 }
  48 int shamt = rs2 & 31;
  49 if (shamt & 16) x = shuffle64_stage(x, 0x0000ffff00000000LL,
  50 0x00000000ffff0000LL, 16); if (shamt & 8) x = shuffle64_stage(x, 0x00ff000000ff0000LL,
  51 0x0000ff000000ff00LL, 8); if (shamt & 4) x = shuffle64_stage(x, 0x0f000f000f000f00LL,
  52 0x00f000f000f000f0LL, 4); if (shamt & 2) x = shuffle64_stage(x, 0x3030303030303030LL,
  53 0x0c0c0c0c0c0c0c0cLL, 2); if (shamt & 1) x = shuffle64_stage(x, 0x4444444444444444LL,
  54 return x;
  55 0x2222222222222222LL, 1);
  56 uint64_t unshfl64(uint64_t rs1, uint64_t rs2) { uint64_t x = rs1;
  57 }
  58 int shamt = rs2 & 31;
  59 if (shamt & 1) x = shuffle64_stage(x, 0x4444444444444444LL,
  60 0x2222222222222222LL, 1); if (shamt & 2) x = shuffle64_stage(x, 0x3030303030303030LL,
  61 0x0c0c0c0c0c0c0c0cLL, 2); if (shamt & 4) x = shuffle64_stage(x, 0x0f000f000f000f00LL,
  62 0x00f000f000f000f0LL, 4); if (shamt & 8) x = shuffle64_stage(x, 0x00ff000000ff0000LL,
  63 0x0000ff000000ff00LL, 8); if (shamt & 16) x = shuffle64_stage(x, 0x0000ffff00000000LL,
  64 return x;
  65 0x00000000ffff0000LL, 16);
  66 ```
  67