217 lines
6.8 KiB
Python
217 lines
6.8 KiB
Python
"""
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This is an auxiliary script that is used to compute valid PLL values to set
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the CPU frequency to a given value. The algorithm here appears as C code
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for the machine.freq() function.
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"""
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from __future__ import print_function
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import re
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def close_int(x):
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return abs(x - round(x)) < 0.01
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# original version that requires N/M to be an integer (for simplicity)
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def compute_pll(hse, sys):
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for P in (2, 4, 6, 8): # allowed values of P
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Q = sys * P / 48
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NbyM = sys * P / hse
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# N/M and Q must be integers
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if not (close_int(NbyM) and close_int(Q)):
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continue
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# VCO_OUT must be between 192MHz and 432MHz
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if not (192 <= hse * NbyM <= 432):
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continue
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# compute M
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M = int(192 // NbyM)
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while hse > 2 * M or NbyM * M < 192:
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M += 1
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# VCO_IN must be between 1MHz and 2MHz (2MHz recommended)
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if not (M <= hse):
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continue
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# compute N
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N = NbyM * M
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# N and Q are restricted
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if not (192 <= N <= 432 and 2 <= Q <= 15):
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continue
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# found valid values
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assert NbyM == N // M
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return (M, N, P, Q)
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# no valid values found
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return None
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# improved version that doesn't require N/M to be an integer
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def compute_pll2(hse, sys, relax_pll48):
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# Loop over the allowed values of P, looking for a valid PLL configuration
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# that gives the desired "sys" frequency. We use floats for P to force
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# floating point arithmetic on Python 2.
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fallback = None
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for P in (2.0, 4.0, 6.0, 8.0):
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NbyM = sys * P / hse
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# VCO_OUT must be between 192MHz and 432MHz
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if not (192 <= hse * NbyM <= 432):
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continue
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# scan M
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M = int(192 // NbyM) # starting value
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while 2 * M < hse:
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M += 1
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# VCO_IN must be between 1MHz and 2MHz (2MHz recommended)
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for M in range(M, hse + 1):
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if NbyM * M < 191.99 or not close_int(NbyM * M):
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continue
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# compute N
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N = NbyM * M
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# N must be an integer
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if not close_int(N):
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continue
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# N is restricted
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if not (192 <= N <= 432):
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continue
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Q = (sys * P / 48)
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# Q must be an integer in a set range
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if not (2 <= Q <= 15):
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continue
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if not close_int(Q):
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if int(M) == int(hse) and fallback is None:
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# the values don't give 48MHz on PLL48 but are otherwise OK
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fallback = M, N, P, int(Q)
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continue
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# found valid values
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return (M, N, P, Q)
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if relax_pll48:
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# might have found values which don't give 48MHz on PLL48
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return fallback
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else:
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# no valid values found which give 48MHz on PLL48
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return None
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def compute_derived(hse, pll):
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M, N, P, Q = pll
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vco_in = hse / M
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vco_out = hse * N / M
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pllck = hse / M * N / P
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pll48ck = hse / M * N / Q
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return (vco_in, vco_out, pllck, pll48ck)
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def verify_pll(hse, pll):
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M, N, P, Q = pll
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vco_in, vco_out, pllck, pll48ck = compute_derived(hse, pll)
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# verify ints
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assert close_int(M)
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assert close_int(N)
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assert close_int(P)
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assert close_int(Q)
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# verify range
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assert 2 <= M <= 63
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assert 192 <= N <= 432
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assert P in (2, 4, 6, 8)
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assert 2 <= Q <= 15
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assert 1 <= vco_in <= 2
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assert 192 <= vco_out <= 432
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def compute_pll_table(source_clk, relax_pll48):
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valid_plls = []
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for sysclk in range(2, 217, 2):
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pll = compute_pll2(source_clk, sysclk, relax_pll48)
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if pll is not None:
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verify_pll(source_clk, pll)
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valid_plls.append((sysclk, pll))
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return valid_plls
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def generate_c_table(hse, valid_plls):
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valid_plls.sort()
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print("// (M, P/2-1, SYS) values for %u MHz source" % hse)
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print("static const uint16_t pll_freq_table[%u] = {" % len(valid_plls))
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for sys, (M, N, P, Q) in valid_plls:
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print(" (%u << 10) | (%u << 8) | %u," % (M, P // 2 - 1, sys))
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print("};")
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def print_table(hse, valid_plls):
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print("HSE =", hse, "MHz")
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print("sys : M N P Q : VCO_IN VCO_OUT PLLCK PLL48CK")
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out_format = "%3u : %2u %.1f %.2f %.2f : %5.2f %6.2f %6.2f %6.2f"
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for sys, pll in valid_plls:
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print(out_format % ((sys,) + pll + compute_derived(hse, pll)))
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print("found %u valid configurations" % len(valid_plls))
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def search_header_for_hsx_values(filename, vals):
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regex_inc = re.compile(r'#include "(boards/[A-Za-z0-9_./]+)"')
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regex_def = re.compile(r'#define +(HSE_VALUE|HSI_VALUE) +\(\(uint32_t\)([0-9]+)\)')
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with open(filename) as f:
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for line in f:
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line = line.strip()
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m = regex_inc.match(line)
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if m:
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# Search included file
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search_header_for_hsx_values(m.group(1), vals)
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continue
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m = regex_def.match(line)
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if m:
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# Found HSE_VALUE or HSI_VALUE
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val = int(m.group(2)) // 1000000
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if m.group(1) == 'HSE_VALUE':
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vals[0] = val
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else:
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vals[1] = val
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return vals
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def main():
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global out_format
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# parse input args
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import sys
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argv = sys.argv[1:]
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c_table = False
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relax_pll48 = False
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hse = None
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hsi = None
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while True:
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if argv[0] == '-c':
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c_table = True
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argv.pop(0)
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elif argv[0] == '--relax-pll48':
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relax_pll48 = True
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argv.pop(0)
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else:
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break
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if len(argv) != 1:
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print("usage: pllvalues.py [-c] <hse in MHz>")
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sys.exit(1)
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if argv[0].startswith("file:"):
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# extract HSE_VALUE, and optionally HSI_VALUE, from header file
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hse, hsi = search_header_for_hsx_values(argv[0][5:], [None, None])
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if hse is None:
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raise ValueError("%s does not contain a definition of HSE_VALUE" % argv[0])
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if hsi is not None and hsi > 16:
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# Currently, a HSI value greater than 16MHz is not supported
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hsi = None
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else:
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# HSE given directly as an integer
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hse = int(argv[0])
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hse_valid_plls = compute_pll_table(hse, relax_pll48)
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if hsi is not None:
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hsi_valid_plls = compute_pll_table(hsi, relax_pll48)
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if c_table:
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print('#if MICROPY_HW_CLK_USE_HSI')
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if hsi is not None:
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hsi_valid_plls.append((hsi, (0, 0, 2, 0)))
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generate_c_table(hsi, hsi_valid_plls)
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print('#else')
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if hsi is not None:
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hse_valid_plls.append((hsi, (0, 0, 2, 0)))
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hse_valid_plls.append((hse, (1, 0, 2, 0)))
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generate_c_table(hse, hse_valid_plls)
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print('#endif')
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else:
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print_table(hse, hse_valid_plls)
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if __name__ == "__main__":
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main()
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