654d1e675a
The x87 FPU supports three floating point formats: 32-bit, 64-bit, and 80-bit floats. The current gem5 implementation supports 32-bit and 64-bit floats, but only works correctly for 64-bit floats. This changeset fixes the 32-bit float handling by correctly loading and rounding (using truncation) 32-bit floats instead of simply truncating the bit pattern. 80-bit floats are loaded by first loading the 80-bits of the float to two temporary integer registers. A micro-op (cvtint_fp80) then converts the contents of the two integer registers to the internal FP representation (double). Similarly, when storing an 80-bit float, there are two conversion routines (ctvfp80h_int and cvtfp80l_int) that convert an internal FP register to 80-bit and stores the upper 64-bits or lower 32-bits to an integer register, which is the written to memory using normal integer stores. |
||
|---|---|---|
| .. | ||
| base.isa | ||
| debug.isa | ||
| fpop.isa | ||
| ldstop.isa | ||
| limmop.isa | ||
| mediaop.isa | ||
| microops.isa | ||
| regop.isa | ||
| seqop.isa | ||
| specop.isa | ||