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jody: fix checkptr segfault #14

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jody: fix checkptr segfault #14

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67 changes: 36 additions & 31 deletions jody/hash.go
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Original file line number Diff line number Diff line change
Expand Up @@ -25,6 +25,13 @@ var mask64 = [...]uint64{
0xffffffffffffffff,
}

func accumulate(data, acc, cons uint64) uint64 {
acc = acc + data + cons
acc = (acc<<shift | acc>>(64-shift)) ^ data
acc = ((acc<<shift | acc>>(64-shift)) ^ cons) + data
return acc
}

// HashString64 returns the hash of s.
func HashString64(s string) uint64 {
return AddString64(Init64, s)
Expand Down Expand Up @@ -88,43 +95,44 @@ func AddString64(h uint64, s string) uint64 {
return hash;
*/

r := *(*reflect.StringHeader)(unsafe.Pointer(&s))
p := unsafe.Pointer((*reflect.StringHeader)(unsafe.Pointer(&s)).Data)
dataLen := len(s)

for n := r.Len / 8; n != 0; n-- {
for dataLen > 8 {
v := *(*uint64)(p)
h = accumulate(v, h, constant)
p = unsafe.Pointer(uintptr(p) + 8)
dataLen -= 8
}

h = h + v + constant
h = (h<<shift | h>>(64-shift)) ^ v
h = ((h<<shift | h>>(64-shift)) ^ constant) + v
if dataLen == 8 {
v := *(*uint64)(p)
return accumulate(v, h, constant)
}

p = unsafe.Pointer(uintptr(p) + 8)
if dataLen == 0 {
return h
}

if n := (r.Len & 7); n != 0 {
c := constant & mask64[n]
v := uint64(0)
off := uint(0)
if 0 != (n & 4) {
v += uint64(*(*uint32)(p))
off += 32
p = unsafe.Pointer(uintptr(p) + 4)
}
if 0 != (n & 2) {
v += uint64(*(*uint16)(p)) << off
off += 16
p = unsafe.Pointer(uintptr(p) + 2)
}
if 0 != (n & 1) {
v += uint64(*(*uint8)(p)) << off
}
// now we have a remainder 1 <= r.Len <= 7

off := uintptr(0)
v := uint64(0)
if 0 != dataLen&4 {
v += uint64(*(*uint32)(unsafe.Pointer(uintptr(p) + off)))
off += 4
}

if 0 != dataLen&2 {
v += uint64(*(*uint16)(unsafe.Pointer(uintptr(p) + off)))
off += 2
}

h = h + v + c
h = (h<<shift | h>>(64-shift)) ^ v
h = ((h<<shift | h>>(64-shift)) ^ c) + v
if 0 != dataLen&1 {
v += uint64(*(*uint8)(unsafe.Pointer(uintptr(p) + off)))
}

return h
return accumulate(v, h, constant&mask64[dataLen])
}

// AddBytes64 adds the hash of b to the precomputed hash value h.
Expand All @@ -134,8 +142,5 @@ func AddBytes64(h uint64, b []byte) uint64 {

// AddUint64 adds the hash value of the 8 bytes of u to h.
func AddUint64(h uint64, u uint64) uint64 {
h = h + u + constant
h = (h<<shift | h>>(64-shift)) ^ u
h = ((h<<shift | h>>(64-shift)) ^ constant) + u
return h
return accumulate(u, h, constant)
}