diff options
| -rw-r--r-- | target-alpha/int_helper.c | 39 |
1 files changed, 26 insertions, 13 deletions
diff --git a/target-alpha/int_helper.c b/target-alpha/int_helper.c index 74f38cbe7b..4a6e95512b 100644 --- a/target-alpha/int_helper.c +++ b/target-alpha/int_helper.c @@ -58,20 +58,33 @@ uint64_t helper_zap(uint64_t val, uint64_t mask) return helper_zapnot(val, ~mask); } -uint64_t helper_cmpbge(uint64_t op1, uint64_t op2) +uint64_t helper_cmpbge(uint64_t a, uint64_t b) { - uint8_t opa, opb, res; - int i; - - res = 0; - for (i = 0; i < 8; i++) { - opa = op1 >> (i * 8); - opb = op2 >> (i * 8); - if (opa >= opb) { - res |= 1 << i; - } - } - return res; + uint64_t mask = 0x00ff00ff00ff00ffULL; + uint64_t test = 0x0100010001000100ULL; + uint64_t al, ah, bl, bh, cl, ch; + + /* Separate the bytes to avoid false positives. */ + al = a & mask; + bl = b & mask; + ah = (a >> 8) & mask; + bh = (b >> 8) & mask; + + /* "Compare". If a byte in B is greater than a byte in A, + it will clear the test bit. */ + cl = ((al | test) - bl) & test; + ch = ((ah | test) - bh) & test; + + /* Fold all of the test bits into a contiguous set. */ + /* ch=.......a...............c...............e...............g........ */ + /* cl=.......b...............d...............f...............h........ */ + cl += ch << 1; + /* cl=......ab..............cd..............ef..............gh........ */ + cl |= cl << 14; + /* cl=......abcd............cdef............efgh............gh........ */ + cl |= cl << 28; + /* cl=......abcdefgh........cdefgh..........efgh............gh........ */ + return cl >> 50; } uint64_t helper_minub8(uint64_t op1, uint64_t op2) |