60 lines
975 B
Plaintext
60 lines
975 B
Plaintext
note
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description: "Summary description for {LIMB_BIT_SCANNING}."
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author: ""
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date: "$Date$"
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revision: "$Revision$"
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deferred class
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LIMB_BIT_SCANNING
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inherit
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LIMB_DEFINITION
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feature
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leading_zeros (limb_a: NATURAL_32): INTEGER
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do
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if limb_a = 0 then
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Result := limb_bits
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else
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Result := count_leading_zeros (limb_a)
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end
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end
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most_significant_one (limb_a: NATURAL_32): INTEGER
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-- 31 high, 0 low
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require
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limb_a /= 0
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do
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Result := limb_high_bit - leading_zeros (limb_a)
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end
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trailing_zeros (limb_a: NATURAL_32): INTEGER
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-- 31 high, 0 low
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require
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limb_a /= 0
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do
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Result := count_trailing_zeros (limb_a)
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end
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feature {NONE} -- Implementation
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count_trailing_zeros (limb_a: NATURAL_32): INTEGER
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external
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"C inline"
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alias
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"[
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return __builtin_ctz ($limb_a);
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]"
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end
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count_leading_zeros (limb_a: NATURAL_32): INTEGER
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external
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"C inline"
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alias
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"[
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return __builtin_clz ($limb_a);
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]"
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end
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end
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