openpower/isa/branch.mdwn

   1 # Branch
   2
   3 I-Form
   4
   5 * b target_addr (AA=0 LK=0)
   6 * ba target_addr (AA=1 LK=0)
   7 * bl target_addr (AA=0 LK=1)
   8 * bla target_addr (AA=1 LK=1)
   9
  10 Pseudo-code:
  11
  12     if AA then NIA  <-iea EXTS(LI || 0b00)
  13     else       NIA  <-iea CIA + EXTS(LI || 0b00)
  14     if LK then LR <-iea  CIA + 4
  15
  16 Special Registers Altered:
  17
  18     LR                       (if LK=1)
  19
  20 # Branch Conditional
  21
  22 B-Form
  23
  24 * bc BO,BI,target_addr (AA=0 LK=0)
  25 * bca BO,BI,target_addr (AA=1 LK=0)
  26 * bcl BO,BI,target_addr (AA=0 LK=1)
  27 * bcla BO,BI,target_addr (AA=1 LK=1)
  28
  29 Pseudo-code:
  30
  31     if (mode_is_64bit) then M <- 0
  32     else M <- 32
  33     if ¬BO[2] then CTR <- CTR - 1
  34     ctr_ok <- BO[2] | ((CTR[M:63] != 0) ^ BO[3])
  35     cond_ok <- BO[0] | ¬(CR[BI+32] ^ BO[1])
  36     if ctr_ok & cond_ok then
  37       if AA then NIA <-iea EXTS(BD || 0b00)
  38       else       NIA <-iea CIA + EXTS(BD || 0b00)
  39     if LK then LR  <-iea  CIA + 4
  40
  41 Special Registers Altered:
  42
  43     CTR                    (if BO2=0)
  44     LR                       (if LK=1)
  45
  46 # Branch Conditional to Link Register
  47
  48 XL-Form
  49
  50 * bclr BO,BI,BH (LK=0)
  51 * bclrl BO,BI,BH (LK=1)
  52
  53 Pseudo-code:
  54
  55     if (mode_is_64bit) then M <- 0
  56     else M <- 32
  57     if ¬BO[2]  then CTR <- CTR - 1
  58     ctr_ok <- BO[2] | ((CTR[M:63] != 0) ^ BO[3])
  59     cond_ok <- BO[0] | ¬(CR[BI+32] ^  BO[1])
  60     if ctr_ok & cond_ok then NIA <-iea LR[0:61] || 0b00
  61     if LK then LR <-iea CIA + 4
  62
  63 Special Registers Altered:
  64
  65     CTR                    (if BO2=0)
  66     LR                       (if LK=1)
  67
  68 # Branch Conditional to Count Register
  69
  70 XL-Form
  71
  72 * bcctr BO,BI,BH (LK=0)
  73 * bcctrl BO,BI,BH (LK=1)
  74
  75 Pseudo-code:
  76
  77     cond_ok <- BO[0] | ¬(CR[BI+32] ^ BO[1])
  78     if cond_ok then NIA <-iea CTR[0:61] || 0b00
  79     if LK then LR <-iea CIA + 4
  80
  81 Special Registers Altered:
  82
  83     LR                     (if LK=1)
  84
  85 # Branch Conditional to Branch Target Address Register
  86
  87 XL-Form
  88
  89 * bctar BO,BI,BH (LK=0)
  90 * bctarl BO,BI,BH (LK=1)
  91
  92 Pseudo-code:
  93
  94     if (mode_is_64bit) then M <- 0
  95     else M <- 32
  96     if ¬BO[2] then CTR <- CTR - 1
  97     ctr_ok <- BO[2]  | ((CTR[M:63] != 0) ^ BO[3])
  98     cond_ok <- BO[0] | ¬(CR[BI+32] ^ BO[1])
  99     if ctr_ok & cond_ok then NIA <-iea TAR[0:61]  || 0b00
 100     if LK then LR <-iea  CIA + 4
 101
 102 Special Registers Altered:
 103
 104     CTR                    (if BO2=0)
 105     LR                       (if LK=1)