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Rewrote enum sign extension with branchless bit operations (also fixes travis)

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gmpreussner
2016-03-15 00:07:18 -04:00
parent e8ff987cef
commit 91d152c0f5
1 changed files with 8 additions and 8 deletions
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16
lib/system/repr.nim
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@@ -74,22 +74,22 @@ proc reprChar(x: char): string {.compilerRtl.} =
proc reprEnum(e: int, typ: PNimType): string {.compilerRtl.} =
# we read an 'int' but this may have been too large, so mask the other bits:
let e = if typ.size == 1: int(int8(e))
elif typ.size == 2: int(int16(e))
elif typ.size == 4: int(int32(e))
else: e
let b = (sizeof(int)-typ.size)*8 # bits
let m = 1 shl (b-1) # mask
var o = e and ((1 shl b)-1) # clear upper bits
o = (o xor m) - m # sign extend
# XXX we need a proper narrowing based on signedness here
#e and ((1 shl (typ.size*8)) - 1)
if ntfEnumHole notin typ.flags:
if e <% typ.node.len:
return $typ.node.sons[e].name
if o <% typ.node.len:
return $typ.node.sons[o].name
else:
# ugh we need a slow linear search:
var n = typ.node
var s = n.sons
for i in 0 .. n.len-1:
if s[i].offset == e: return $s[i].name
result = $e & " (invalid data!)"
if s[i].offset == o: return $s[i].name
result = $o & " (invalid data!)"
type
PByteArray = ptr array[0.. 0xffff, int8]