Bug 97

Summary: FP16 mul bug
Product: Libre-SOC's first SoC Reporter: Luke Kenneth Casson Leighton <lkcl>
Component: ALU (including IEEE754 16/32/64-bit FPU)Assignee: Luke Kenneth Casson Leighton <lkcl>
Status: RESOLVED FIXED    
Severity: enhancement CC: libre-soc-bugs
Priority: ---    
Version: unspecified   
Hardware: PC   
OS: Linux   
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Description Luke Kenneth Casson Leighton 2019-06-16 13:42:27 BST
bug, 0xe225 0x8181 0x249f returns 0x249e
Comment 1 Luke Kenneth Casson Leighton 2019-06-16 13:51:10 BST
send 0 3 0xf73b 0x802e 0x2d32
recv 0 0x2d30 expected 0x2d32
Comment 2 Luke Kenneth Casson Leighton 2019-07-16 10:49:14 BST
fixed: was related to the normalisation phases being entirely missing.
tiny numbers just above zero were entering the MUL phase with the
mantissa not being '1' in the MSB.  consequently the product was
nowhere near accurate.

fixed by shifting both A and B up so that the mantissa always has "1"
in the MSB.