openpower/sv/fclass.mdwn

   1 # fclass
   2
   3 xvtstdcsp v3.0B p768
   4
   5 | 0.5|6.10|11.15|16.18 | 19.26  | 27...30 |31|  name   |
   6 | -- | -- | --- | ---- | ------ | ------- |--| ------- |
   7 | PO | RT | FRA | BA   | DCMX   | XO[0:3] |Rc| fptstsp |
   8
   9 ```
  10 src  <- (FRA)[32:63]
  11 sign  <- src[0]
  12 exponent  <- src[1:8]
  13 fraction  <- src[9:31]
  14 class.Infinity  <- (exponent = 0xFF) & (fraction = 0)
  15 class.NaN  <- (exponent = 0xFF) & (fraction != 0)
  16 class.Zero  <- (exponent = 0x00) & (fraction = 0)
  17 class.Denormal  <- (exponent = 0x00) & (fraction != 0)
  18 match <- (DCMX[0] & class.NaN & !sign)  |
  19          (DCMX[1] & class.NaN & sign)  |
  20          (DCMX[2] & class.Infinity & !sign) |
  21          (DCMX[3] & class.Infinity & sign) |
  22          (DCMX[4] & class.Zero & !sign) |
  23          (DCMX[5] & class.Zero & sign) |
  24          (DCMX[6] & class.Denormal & !sign) |
  25          (DCMX[7] & class.Denormal & sign)
  26
  27 if match = 1 then
  28     RT[32:63] <- 0xFFFF_FFFF
  29 else
  30     RT[32:63] <- 0x0000_0000
  31 end
  32 CR{BA} = class.Zero ||
  33          class.Infinity ||
  34          class.Denormal ||
  35          class.NaN
  36 ```