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vendor.GowinPlatform: improve oscillator frequency diagnostic.

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This commit is contained in:
Catherine 2023-09-02 21:26:35 +00:00
parent 05cb82b8fc
commit bfd62569c8
1 changed files with 15 additions and 9 deletions
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24
amaranth/vendor/_gowin.py
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@ -1,5 +1,6 @@
from abc import abstractproperty
from fractions import Fraction
import math
import re
from ..hdl import *
@ -160,17 +161,22 @@ class GowinPlatform(TemplatedPlatform):
@property
def _osc_div(self):
div_min = 2
div_max = 128
div_step = 2
div_frac = Fraction(self._osc_base_freq, self.osc_frequency)
div_range = range(2, 128, 2)
div_frac = Fraction(self._osc_base_freq, self.osc_frequency)
if div_frac.denominator != 1 or div_frac not in range(div_min, div_max, div_step):
if div_frac.denominator != 1 or div_frac not in div_range:
achievable = (
min((frac for frac in div_range if frac > div_frac), default=None),
max((frac for frac in div_range if frac < div_frac), default=None)
)
raise ValueError(
"On-chip oscillator frequency (platform.osc_frequency) must be chosen such that "
"the oscillator divider, calculated as ({}/{}), is an integer between {} and {} in "
"steps of {}"
.format(div_frac.numerator, div_frac.denominator, div_min, div_max, div_step))
f"On-chip oscillator frequency (platform.osc_frequency) must be chosen such that "
f"the base frequency of {self._osc_base_freq} Hz is divided by an integer factor "
f"between {div_range.start} and {div_range.stop} in steps of {div_range.step}; "
f"the divider for the requested frequency of {self.osc_frequency} Hz was "
f"calculated as ({div_frac.numerator}/{div_frac.denominator}), and the closest "
f"achievable frequencies are " +
", ".join(str(self._osc_base_freq // frac) for frac in achievable if frac))
return div_frac.numerator