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28a181ff81
Improve the tool that finds multiplier and divider for PLLs: The previous algorithm could get stuck on local maxima and required the user to specify the tolerance. Improve the algorithm to go through the entire search space and find the optimal solution. Signed-off-by: Aneesh V <aneesh@ti.com>
202 lines
6.4 KiB
C
202 lines
6.4 KiB
C
/*
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* Program for finding M & N values for DPLLs
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* To be run on Host PC
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*
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* (C) Copyright 2010
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* Texas Instruments, <www.ti.com>
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*
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* Aneesh V <aneesh@ti.com>
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*
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* See file CREDITS for list of people who contributed to this
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* project.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation; either version 2 of
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* the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston,
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* MA 02111-1307 USA
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*/
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#include <stdlib.h>
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#include <stdio.h>
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typedef unsigned int u32;
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#define MAX_N 127
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/*
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* get_m_n_optimized() - Finds optimal DPLL multiplier(M) and divider(N)
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* values based on the reference frequency, required output frequency,
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* maximum tolerance for output frequency etc.
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*
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* target_freq_khz - output frequency required in KHz
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* ref_freq_khz - reference(input) frequency in KHz
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* m - pointer to computed M value
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* n - pointer to computed N value
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* tolerance_khz - tolerance for the output frequency. When the algorithm
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* succeeds in finding vialble M and N values the corresponding output
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* frequency will be in the range:
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* [target_freq_khz - tolerance_khz, target_freq_khz]
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*
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* Formula:
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* Fdpll = (2 * M * Fref) / (N + 1)
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*
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* Considerations for lock-time:
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* - Smaller the N, better lock-time, especially lock-time will be
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* - For acceptable lock-times:
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* Fref / (M + 1) >= 1 MHz
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*
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* Considerations for power:
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* - The difference in power for different N values giving the same
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* output is negligible. So, we optimize for lock-time
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*
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* Hard-constraints:
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* - N can not be greater than 127(7 bit field for representing N)
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*
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* Usage:
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* $ gcc clocks_get_m_n.c
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* $ ./a.out
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*/
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int get_m_n_optimized(u32 target_freq_khz, u32 ref_freq_khz, u32 *M, u32 *N)
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{
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u32 freq = target_freq_khz;
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u32 m_optimal, n_optimal, freq_optimal = 0, freq_old;
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u32 m, n;
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n = 1;
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while (1) {
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m = target_freq_khz / ref_freq_khz / 2 * n;
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freq_old = 0;
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while (1) {
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freq = ref_freq_khz * 2 * m / n;
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if (freq > target_freq_khz) {
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freq = freq_old;
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m--;
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break;
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}
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m++;
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freq_old = freq;
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}
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if (freq > freq_optimal) {
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freq_optimal = freq;
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m_optimal = m;
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n_optimal = n;
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}
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n++;
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if ((freq_optimal == target_freq_khz) ||
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((ref_freq_khz / n) < 1000)) {
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break;
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}
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}
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n--;
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*M = m_optimal;
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*N = n_optimal - 1;
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printf("ref %d m %d n %d target %d locked %d\n", ref_freq_khz,
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m_optimal, n_optimal - 1, target_freq_khz, freq_optimal);
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return 0;
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}
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void main(void)
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{
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u32 m, n;
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printf("\nMPU - 2000000\n");
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get_m_n_optimized(2000000, 12000, &m, &n);
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get_m_n_optimized(2000000, 13000, &m, &n);
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get_m_n_optimized(2000000, 16800, &m, &n);
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get_m_n_optimized(2000000, 19200, &m, &n);
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get_m_n_optimized(2000000, 26000, &m, &n);
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get_m_n_optimized(2000000, 27000, &m, &n);
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get_m_n_optimized(2000000, 38400, &m, &n);
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printf("\nMPU - 1200000\n");
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get_m_n_optimized(1200000, 12000, &m, &n);
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get_m_n_optimized(1200000, 13000, &m, &n);
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get_m_n_optimized(1200000, 16800, &m, &n);
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get_m_n_optimized(1200000, 19200, &m, &n);
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get_m_n_optimized(1200000, 26000, &m, &n);
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get_m_n_optimized(1200000, 27000, &m, &n);
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get_m_n_optimized(1200000, 38400, &m, &n);
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printf("\nMPU - 1584000\n");
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get_m_n_optimized(1584000, 12000, &m, &n);
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get_m_n_optimized(1584000, 13000, &m, &n);
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get_m_n_optimized(1584000, 16800, &m, &n);
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get_m_n_optimized(1584000, 19200, &m, &n);
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get_m_n_optimized(1584000, 26000, &m, &n);
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get_m_n_optimized(1584000, 27000, &m, &n);
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get_m_n_optimized(1584000, 38400, &m, &n);
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printf("\nCore 1600000\n");
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get_m_n_optimized(1600000, 12000, &m, &n);
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get_m_n_optimized(1600000, 13000, &m, &n);
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get_m_n_optimized(1600000, 16800, &m, &n);
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get_m_n_optimized(1600000, 19200, &m, &n);
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get_m_n_optimized(1600000, 26000, &m, &n);
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get_m_n_optimized(1600000, 27000, &m, &n);
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get_m_n_optimized(1600000, 38400, &m, &n);
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printf("\nPER 1536000\n");
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get_m_n_optimized(1536000, 12000, &m, &n);
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get_m_n_optimized(1536000, 13000, &m, &n);
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get_m_n_optimized(1536000, 16800, &m, &n);
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get_m_n_optimized(1536000, 19200, &m, &n);
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get_m_n_optimized(1536000, 26000, &m, &n);
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get_m_n_optimized(1536000, 27000, &m, &n);
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get_m_n_optimized(1536000, 38400, &m, &n);
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printf("\nIVA 1862000\n");
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get_m_n_optimized(1862000, 12000, &m, &n);
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get_m_n_optimized(1862000, 13000, &m, &n);
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get_m_n_optimized(1862000, 16800, &m, &n);
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get_m_n_optimized(1862000, 19200, &m, &n);
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get_m_n_optimized(1862000, 26000, &m, &n);
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get_m_n_optimized(1862000, 27000, &m, &n);
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get_m_n_optimized(1862000, 38400, &m, &n);
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printf("\nIVA Nitro - 1290000\n");
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get_m_n_optimized(1290000, 12000, &m, &n);
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get_m_n_optimized(1290000, 13000, &m, &n);
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get_m_n_optimized(1290000, 16800, &m, &n);
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get_m_n_optimized(1290000, 19200, &m, &n);
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get_m_n_optimized(1290000, 26000, &m, &n);
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get_m_n_optimized(1290000, 27000, &m, &n);
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get_m_n_optimized(1290000, 38400, &m, &n);
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printf("\nABE 196608 sys clk\n");
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get_m_n_optimized(196608, 12000, &m, &n);
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get_m_n_optimized(196608, 13000, &m, &n);
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get_m_n_optimized(196608, 16800, &m, &n);
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get_m_n_optimized(196608, 19200, &m, &n);
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get_m_n_optimized(196608, 26000, &m, &n);
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get_m_n_optimized(196608, 27000, &m, &n);
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get_m_n_optimized(196608, 38400, &m, &n);
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printf("\nABE 196608 32K\n");
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get_m_n_optimized(196608000/4, 32768, &m, &n);
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printf("\nUSB 1920000\n");
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get_m_n_optimized(1920000, 12000, &m, &n);
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get_m_n_optimized(1920000, 13000, &m, &n);
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get_m_n_optimized(1920000, 16800, &m, &n);
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get_m_n_optimized(1920000, 19200, &m, &n);
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get_m_n_optimized(1920000, 26000, &m, &n);
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get_m_n_optimized(1920000, 27000, &m, &n);
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get_m_n_optimized(1920000, 38400, &m, &n);
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printf("\nCore ES1 1523712\n");
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get_m_n_optimized(1524000, 12000, &m, &n);
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get_m_n_optimized(1524000, 13000, &m, &n);
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get_m_n_optimized(1524000, 16800, &m, &n);
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get_m_n_optimized(1524000, 19200, &m, &n);
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get_m_n_optimized(1524000, 26000, &m, &n);
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get_m_n_optimized(1524000, 27000, &m, &n);
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/* exact recommendation for SDPs */
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get_m_n_optimized(1523712, 38400, &m, &n);
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}
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