94 lines
2.4 KiB
Text
94 lines
2.4 KiB
Text
/-
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Copyright (c) 2022 Henrik Böving. All rights reserved.
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Released under Apache 2.0 license as described in the file LICENSE.
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Authors: Henrik Böving
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-/
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module
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prelude
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import Init.Data.Fin.Log2
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/--
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Base-two logarithm of 8-bit unsigned integers. Returns `⌊max 0 (log₂ a)⌋`.
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This function is overridden at runtime with an efficient implementation. This definition is
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the logical model.
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Examples:
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* `UInt8.log2 0 = 0`
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* `UInt8.log2 1 = 0`
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* `UInt8.log2 2 = 1`
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* `UInt8.log2 4 = 2`
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* `UInt8.log2 7 = 2`
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* `UInt8.log2 8 = 3`
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-/
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@[extern "lean_uint8_log2"]
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def UInt8.log2 (a : UInt8) : UInt8 := ⟨⟨Fin.log2 a.toFin⟩⟩
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/--
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Base-two logarithm of 16-bit unsigned integers. Returns `⌊max 0 (log₂ a)⌋`.
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This function is overridden at runtime with an efficient implementation. This definition is
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the logical model.
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Examples:
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* `UInt16.log2 0 = 0`
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* `UInt16.log2 1 = 0`
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* `UInt16.log2 2 = 1`
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* `UInt16.log2 4 = 2`
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* `UInt16.log2 7 = 2`
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* `UInt16.log2 8 = 3`
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-/
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@[extern "lean_uint16_log2"]
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def UInt16.log2 (a : UInt16) : UInt16 := ⟨⟨Fin.log2 a.toFin⟩⟩
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/--
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Base-two logarithm of 32-bit unsigned integers. Returns `⌊max 0 (log₂ a)⌋`.
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This function is overridden at runtime with an efficient implementation. This definition is
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the logical model.
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Examples:
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* `UInt32.log2 0 = 0`
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* `UInt32.log2 1 = 0`
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* `UInt32.log2 2 = 1`
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* `UInt32.log2 4 = 2`
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* `UInt32.log2 7 = 2`
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* `UInt32.log2 8 = 3`
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-/
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@[extern "lean_uint32_log2"]
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def UInt32.log2 (a : UInt32) : UInt32 := ⟨⟨Fin.log2 a.toFin⟩⟩
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/--
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Base-two logarithm of 64-bit unsigned integers. Returns `⌊max 0 (log₂ a)⌋`.
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This function is overridden at runtime with an efficient implementation. This definition is
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the logical model.
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Examples:
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* `UInt64.log2 0 = 0`
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* `UInt64.log2 1 = 0`
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* `UInt64.log2 2 = 1`
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* `UInt64.log2 4 = 2`
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* `UInt64.log2 7 = 2`
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* `UInt64.log2 8 = 3`
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-/
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@[extern "lean_uint64_log2"]
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def UInt64.log2 (a : UInt64) : UInt64 := ⟨⟨Fin.log2 a.toFin⟩⟩
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/--
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Base-two logarithm of word-sized unsigned integers. Returns `⌊max 0 (log₂ a)⌋`.
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This function is overridden at runtime with an efficient implementation. This definition is
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the logical model.
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Examples:
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* `USize.log2 0 = 0`
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* `USize.log2 1 = 0`
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* `USize.log2 2 = 1`
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* `USize.log2 4 = 2`
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* `USize.log2 7 = 2`
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* `USize.log2 8 = 3`
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-/
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@[extern "lean_usize_log2"]
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def USize.log2 (a : USize) : USize := ⟨⟨Fin.log2 a.toFin⟩⟩
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