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107 lines
2.2 KiB
C++
107 lines
2.2 KiB
C++
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/*
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* M_APM - mapmpwr2.c
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*
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* Copyright (C) 2002 - 2007 Michael C. Ring
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*
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* Permission to use, copy, and distribute this software and its
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* documentation for any purpose with or without fee is hereby granted,
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* provided that the above copyright notice appear in all copies and
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* that both that copyright notice and this permission notice appear
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* in supporting documentation.
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*
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* Permission to modify the software is granted. Permission to distribute
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* the modified code is granted. Modifications are to be distributed by
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* using the file 'license.txt' as a template to modify the file header.
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* 'license.txt' is available in the official MAPM distribution.
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*
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* This software is provided "as is" without express or implied warranty.
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*/
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/*
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* This file contains the Integer Power function and the result
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* is NOT ROUNDED. The exponent must be an integer >= zero.
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*
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* This will typically be used in an application where full integer
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* precision is required to be maintained.
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*
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*/
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#include "pgAdmin3.h"
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#include "pgscript/utilities/mapm-lib/m_apm_lc.h"
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/****************************************************************************/
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void m_apm_integer_pow_nr(M_APM rr, M_APM aa, int mexp)
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{
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M_APM tmp0, tmpy, tmpz;
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int nexp, ii;
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if (mexp == 0)
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{
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m_apm_copy(rr, MM_One);
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return;
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}
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else
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{
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if (mexp < 0)
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{
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M_apm_log_error_msg(M_APM_RETURN,
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"\'m_apm_integer_pow_nr\', Negative exponent");
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M_set_to_zero(rr);
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return;
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}
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}
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if (mexp == 1)
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{
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m_apm_copy(rr, aa);
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return;
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}
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if (mexp == 2)
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{
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m_apm_multiply(rr, aa, aa);
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return;
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}
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nexp = mexp;
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if (aa->m_apm_sign == 0)
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{
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M_set_to_zero(rr);
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return;
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}
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tmp0 = M_get_stack_var();
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tmpy = M_get_stack_var();
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tmpz = M_get_stack_var();
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m_apm_copy(tmpy, MM_One);
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m_apm_copy(tmpz, aa);
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while (TRUE)
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{
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ii = nexp & 1;
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nexp = nexp >> 1;
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if (ii != 0) /* exponent -was- odd */
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{
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m_apm_multiply(tmp0, tmpy, tmpz);
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if (nexp == 0)
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break;
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m_apm_copy(tmpy, tmp0);
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}
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m_apm_multiply(tmp0, tmpz, tmpz);
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m_apm_copy(tmpz, tmp0);
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}
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m_apm_copy(rr, tmp0);
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M_restore_stack(3);
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}
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/****************************************************************************/
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