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nga-python: n:MIN and n:MAX queries now reporting a 128-bit range (#30) along with some comments regarding this

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FossilOrigin-Name: 1998a44c226313a0e86b635f10fb6fb06ed6698fd62a75e81f1a6a22883ae125
This commit is contained in:
crc 2020-12-22 12:41:42 +00:00
parent f05a03d167
commit 84f5134687
1 changed files with 18 additions and 3 deletions
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21
vm/nga-python/retro.py
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@ -253,6 +253,22 @@ class Retro:
else:
self.stack.push(0)
# The fetch instruction also handles certain
# introspection queries.
#
# Of note is the min and max values for a cell.
# In most VM implementations, this is limited
# to 32 bit or 64 bit ranges, but Python allows
# an unlimited range.
#
# I report as if the cells are capped at 128 bits
# but you can safely ignore this if running on
# the Python VM. (This does have an impact on
# floating point values, if using the `e:` words
# for converting them to/from an encoded format in
# standard cells, but should not affect anything
# else in the standard system)
def i_fetch(self):
target = self.stack.pop()
if target >= 0:
@ -266,13 +282,12 @@ class Retro:
elif target == -3:
self.stack.push(self.memory.size())
elif target == -4:
self.stack.push(2147483648)
self.stack.push(-170141183460469231731687303715884105728)
elif target == -5:
self.stack.push(2147483647)
self.stack.push(170141183460469231731687303715884105727)
else:
self.stack.push(0)
def i_store(self):
mi = self.stack.pop()
self.memory[mi] = self.stack.pop()