Fix pgm_read_float_unaligned macro #6593
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Fixes esp8266#6590 The ASM block that implements the read-uint32-unaligned returns a uint32_t. The old code was doing a cast like `(float)(uint32_t ret) which actually goes and creates a new float of the positive uint value (approx, of course due to exponent and sign bits) which is not correct. C and C++ don't have a concise way to convert the bits in a register from int to float interpretation, so avoid the whole issue by making a new function which uses the same ASM block as the read-uint32-unaligned, just make the destination and return values as floats.
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Good catch, @maxint-rd! |
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Fixes #6590
The ASM block that implements the read-uint32-unaligned returns a
uint32_t. The old code was doing a cast like `(float)(uint32_t ret)
which actually goes and creates a new float of the positive uint value
(approx, of course due to exponent and sign bits) which is not correct.
C and C++ don't have a concise way to convert the bits in a register
from int to float interpretation, so avoid the whole issue by making a
new function which uses the same ASM block as the read-uint32-unaligned,
just make the destination and return values as floats.