2fe8fb192f
There is important information about booting non-ack images in docs/UPDATING. ack/aout-format images can't be built any more, and booting clang/ELF-format ones is a little different. Updating to the new boot monitor is recommended. Changes in this commit: . drop boot monitor -> allowing dropping ack support . facility to copy ELF boot files to /boot so that old boot monitor can still boot fairly easily, see UPDATING . no more ack-format libraries -> single-case libraries . some cleanup of OBJECT_FMT, COMPILER_TYPE, etc cases . drop several ack toolchain commands, but not all support commands (e.g. aal is gone but acksize is not yet). . a few libc files moved to netbsd libc dir . new /bin/date as minix date used code in libc/ . test compile fix . harmonize includes . /usr/lib is no longer special: without ack, /usr/lib plays no kind of special bootstrapping role any more and bootstrapping is done exclusively through packages, so releases depend even less on the state of the machine making them now. . rename nbsd_lib* to lib* . reduce mtree
77 lines
1.8 KiB
ArmAsm
77 lines
1.8 KiB
ArmAsm
/*
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* Written by J.T. Conklin <jtc@NetBSD.org>.
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* Public domain.
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*/
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/*
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* Modified by Lex Wennmacher <wennmach@NetBSD.org>
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* Still public domain.
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*/
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#include <machine/asm.h>
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#include "abi.h"
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RCSID("$NetBSD: s_log1p.S,v 1.13 2003/09/16 18:17:11 wennmach Exp $")
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/*
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* The log1p() function is provided to compute an accurate value of
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* log(1 + x), even for tiny values of x. The i387 FPU provides the
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* fyl2xp1 instruction for this purpose. However, the range of this
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* instruction is limited to:
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* -(1 - (sqrt(2) / 2)) <= x <= sqrt(2) - 1
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* -0.292893 <= x <= 0.414214
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* at least on older processor versions.
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*
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* log1p() is implemented by testing the range of the argument.
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* If it is appropriate for fyl2xp1, this instruction is used.
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* Else, we compute log1p(x) = ln(2)*ld(1 + x) the traditional way
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* (using fyl2x).
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*
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* The range testing costs speed, but as the rationale for the very
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* existence of this function is accuracy, we accept that.
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*
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* In order to reduce the cost for testing the range, we check if
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* the argument is in the range
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* -0.25 <= x <= 0.25
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* which can be done with just one conditional branch. If x is
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* inside this range, we use fyl2xp1. Outside of this range,
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* the use of fyl2x is accurate enough.
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*
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*/
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.text
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.align 4
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ENTRY(log1p)
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XMM_ONE_ARG_DOUBLE_PROLOGUE
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fldl ARG_DOUBLE_ONE
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fabs
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fld1 /* ... x 1 */
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fadd %st(0) /* ... x 2 */
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fadd %st(0) /* ... x 4 */
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fld1 /* ... 4 1 */
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fdivp /* ... x 0.25 */
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fcompp
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fnstsw %ax
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andb $69,%ah
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jne use_fyl2x
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jmp use_fyl2xp1
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.align 4
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use_fyl2x:
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fldln2
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fldl ARG_DOUBLE_ONE
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fld1
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faddp
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fyl2x
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XMM_DOUBLE_EPILOGUE
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ret
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.align 4
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use_fyl2xp1:
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fldln2
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fldl ARG_DOUBLE_ONE
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fyl2xp1
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XMM_DOUBLE_EPILOGUE
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ret
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