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/*
* M_APM - mapm_pow.c
*
* Copyright (C) 2000 - 2007 Michael C. Ring
*
* Permission to use, copy, and distribute this software and its
* documentation for any purpose with or without fee is hereby granted,
* provided that the above copyright notice appear in all copies and
* that both that copyright notice and this permission notice appear
* in supporting documentation.
*
* Permission to modify the software is granted. Permission to distribute
* the modified code is granted. Modifications are to be distributed by
* using the file 'license.txt' as a template to modify the file header.
* 'license.txt' is available in the official MAPM distribution.
*
* This software is provided "as is" without express or implied warranty.
*/
/*
*
* This file contains the POW function.
*
*/
#include "pgAdmin3.h"
#include "pgscript/utilities/mapm-lib/m_apm_lc.h"
static M_APM M_last_xx_input;
static M_APM M_last_xx_log;
static int M_last_log_digits;
static int M_size_flag = 0;
/****************************************************************************/
void M_free_all_pow()
{
if (M_size_flag != 0)
{
m_apm_free(M_last_xx_input);
m_apm_free(M_last_xx_log);
M_size_flag = 0;
}
}
/****************************************************************************/
/*
Calculate the POW function by calling EXP :
Y A
X = e where A = Y * log(X)
*/
void m_apm_pow(M_APM rr, int places, M_APM xx, M_APM yy)
{
int iflag, pflag;
char sbuf[64];
M_APM tmp8, tmp9;
/* if yy == 0, return 1 */
if (yy->m_apm_sign == 0)
{
m_apm_copy(rr, MM_One);
return;
}
/* if xx == 0, return 0 */
if (xx->m_apm_sign == 0)
{
M_set_to_zero(rr);
return;
}
if (M_size_flag == 0) /* init locals on first call */
{
M_size_flag = M_get_sizeof_int();
M_last_log_digits = 0;
M_last_xx_input = m_apm_init();
M_last_xx_log = m_apm_init();
}
/*
* if 'yy' is a small enough integer, call the more
* efficient _integer_pow function.
*/
if (m_apm_is_integer(yy))
{
iflag = FALSE;
if (M_size_flag == 2) /* 16 bit compilers */
{
if (yy->m_apm_exponent <= 4)
iflag = TRUE;
}
else /* >= 32 bit compilers */
{
if (yy->m_apm_exponent <= 7)
iflag = TRUE;
}
if (iflag)
{
m_apm_to_integer_string(sbuf, yy);
m_apm_integer_pow(rr, places, xx, atoi(sbuf));
return;
}
}
tmp8 = M_get_stack_var();
tmp9 = M_get_stack_var();
/*
* If parameter 'X' is the same this call as it
* was the previous call, re-use the saved log
* calculation from last time.
*/
pflag = FALSE;
if (M_last_log_digits >= places)
{
if (m_apm_compare(xx, M_last_xx_input) == 0)
pflag = TRUE;
}
if (pflag)
{
m_apm_round(tmp9, (places + 8), M_last_xx_log);
}
else
{
m_apm_log(tmp9, (places + 8), xx);
M_last_log_digits = places + 2;
/* save the 'X' input value and the log calculation */
m_apm_copy(M_last_xx_input, xx);
m_apm_copy(M_last_xx_log, tmp9);
}
m_apm_multiply(tmp8, tmp9, yy);
m_apm_exp(rr, places, tmp8);
M_restore_stack(2); /* restore the 2 locals we used here */
}
/****************************************************************************/
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