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torvalds
GitHub Repository: torvalds/linux
 Path: blob/master/arch/x86/math-emu/shr_Xsig.S
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/* SPDX-License-Identifier: GPL-2.0 */

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	.file	"shr_Xsig.S"

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/*---------------------------------------------------------------------------+

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 |  shr_Xsig.S                                                               |

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 |                                                                           |

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 | 12 byte right shift function                                              |

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 |                                                                           |

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 | Copyright (C) 1992,1994,1995                                              |

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 |                       W. Metzenthen, 22 Parker St, Ormond, Vic 3163,      |

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 |                       Australia.  E-mail [email protected] |

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 |                                                                           |

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 | Call from C as:                                                           |

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 |   void shr_Xsig(Xsig *arg, unsigned nr)                                   |

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 |                                                                           |

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 |   Extended shift right function.                                          |

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 |   Fastest for small shifts.                                               |

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 |   Shifts the 12 byte quantity pointed to by the first arg (arg)           |

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 |   right by the number of bits specified by the second arg (nr).           |

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 |                                                                           |

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 +---------------------------------------------------------------------------*/

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#include "fpu_emu.h"

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.text

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SYM_FUNC_START(shr_Xsig)

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	push	%ebp

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	movl	%esp,%ebp

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	pushl	%esi

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	movl	PARAM2,%ecx

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	movl	PARAM1,%esi

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	cmpl	$32,%ecx	/* shrd only works for 0..31 bits */

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	jnc	L_more_than_31

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/* less than 32 bits */

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	pushl	%ebx

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	movl	(%esi),%eax	/* lsl */

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	movl	4(%esi),%ebx	/* midl */

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	movl	8(%esi),%edx	/* msl */

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	shrd	%cl,%ebx,%eax

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	shrd	%cl,%edx,%ebx

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	shr	%cl,%edx

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	movl	%eax,(%esi)

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	movl	%ebx,4(%esi)

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	movl	%edx,8(%esi)

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	popl	%ebx

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	popl	%esi

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	leave

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	RET

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L_more_than_31:

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	cmpl	$64,%ecx

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	jnc	L_more_than_63

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	subb	$32,%cl

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	movl	4(%esi),%eax	/* midl */

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	movl	8(%esi),%edx	/* msl */

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	shrd	%cl,%edx,%eax

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	shr	%cl,%edx

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	movl	%eax,(%esi)

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	movl	%edx,4(%esi)

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	movl	$0,8(%esi)

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	popl	%esi

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	leave

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	RET

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L_more_than_63:

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	cmpl	$96,%ecx

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	jnc	L_more_than_95

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	subb	$64,%cl

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	movl	8(%esi),%eax	/* msl */

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	shr	%cl,%eax

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	xorl	%edx,%edx

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	movl	%eax,(%esi)

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	movl	%edx,4(%esi)

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	movl	%edx,8(%esi)

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	popl	%esi

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	leave

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	RET

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L_more_than_95:

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	xorl	%eax,%eax

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	movl	%eax,(%esi)

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	movl	%eax,4(%esi)

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	movl	%eax,8(%esi)

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	popl	%esi

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	leave

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	RET

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SYM_FUNC_END(shr_Xsig)

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