121 lines
1.8 KiB
NASM
121 lines
1.8 KiB
NASM
title "Byte Swap Functions"
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;++
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;
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; Copyright (c) 1997 Microsoft Corporation
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;
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; Module Name:
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;
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; movemem.asm
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;
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; Abstract:
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;
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; This module implements functions to perform byte swapping operations.
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;
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;
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; Author:
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;
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; Forrest Foltz (forrestf) 12-Dec-1997
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;
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; Environment:
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;
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; User or Kernel mode.
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;
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; Revision History:
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;
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;--
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.486p
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.xlist
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include ks386.inc
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include callconv.inc ; calling convention macros
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.list
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;
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; Alignment for functions in this module
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;
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CODE_ALIGNMENT macro
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align 16
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endm
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_TEXT SEGMENT PARA PUBLIC 'CODE'
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ASSUME DS:FLAT, ES:FLAT, SS:NOTHING, FS:NOTHING, GS:NOTHING
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PAGE
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SUBTTL "RtlUshortByteSwap"
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;++
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;
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; USHORT
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; RtlUshortByteSwap(
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; IN USHORT Source
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; )
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;
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; /*++
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;
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; Routine Description:
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;
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; The RtlfUshortByteSwap function exchanges bytes 0 and 1 of Source
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; and returns the resulting USHORT.
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;
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; Arguments:
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;
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; (cx) Source - 16-bit value to byteswap.
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;
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; Return Value:
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;
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; Swapped 16-bit value.
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;
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;--
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CODE_ALIGNMENT
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cPublicFastCall RtlUshortByteSwap ,1
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cPublicFpo 0, 0
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mov ah, cl
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mov al, ch
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fstRET RtlUshortByteSwap
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fstENDP RtlUshortByteSwap
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PAGE
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SUBTTL "RtlUlongByteSwap"
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;++
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;
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; ULONG
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; RtlUlongByteSwap(
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; IN ULONG Source
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; )
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;
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; /*++
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;
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; Routine Description:
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;
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; The RtlUlongByteSwap function exchanges byte pairs 0:3 and 1:2 of
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; Source and returns the the resulting ULONG.
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;
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; Arguments:
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;
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; (ecx) Source - 32-bit value to byteswap.
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;
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; Return Value:
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;
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; Swapped 32-bit value.
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;
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;--
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CODE_ALIGNMENT
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cPublicFastCall RtlUlongByteSwap ,1
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cPublicFpo 0, 0
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mov eax, ecx
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bswap eax
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fstRET RtlUlongByteSwap
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fstENDP RtlUlongByteSwap
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_TEXT ends
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end
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