Hi Alex, Here's my first adjustment to your conversion for 128-bit floats.
The Idea is to use a set of macros and an include file so that we can re-use the same large chunk of code that performs the basic operations on various fraction lengths. It's ugly, but without proper language support it seems to be less ugly than most. While I've just gone and added lots of stuff to int128... I have had another idea, half-baked because I'm tired and it's late: typedef struct { FloatClass cls; int exp; bool sign; uint64_t frac[]; } FloatPartsBase; typedef struct { FloatPartsBase base; uint64_t frac; } FloatParts64; typedef struct { FloatPartsBase base; uint64_t frac_hi, frac_lo; } FloatParts128; typedef struct { FloatPartsBase base; uint64_t frac[4]; /* big endian word ordering */ } FloatParts256; This layout, with the big-endian ordering, means that storage can be shared between them, just by ignoring the least significant words of the fraction as needed. Which may make muladd more understandable. E.g. static void muladd_floats64(FloatParts128 *r, FloatParts64 *a, FloatParts64 *b, FloatParts128 *c, ...) { // handle nans // produce 128-bit product into r // handle p vs c special cases. // zero-extend c to 128-bits c->frac[1] = 0; // perform 128-bit fractional addition addsub_floats128(r, c, ...); // fold 128-bit fraction to 64-bit sticky bit. r->frac[0] |= r->frac[1] != 0; } float64 float64_muladd(float64 a, float64 b, float64 c, ...) { FloatParts64 pa, pb; FloatParts128 pc, pr; float64_unpack_canonical(&pa.base, a, status); float64_unpack_canonical(&pb.base, b, status); float64_unpack_canonical(&pc.base, c, status); muladd_floats64(&pr, &pa, &pb, &pc, flags, status); return float64_round_pack_canonical(&pr.base, status); } Similarly, muladd_floats128 would use addsub_floats256. However, the big-endian word ordering means that Int128 cannot be used directly; so a set of wrappers are needed. If added the Int128 routine just for use here, then it's probably easier to bypass Int128 and just code it here. Thoughts? r~ Richard Henderson (15): qemu/int128: Add int128_or qemu/int128: Add int128_clz, int128_ctz qemu/int128: Rename int128_rshift, int128_lshift qemu/int128: Add int128_shr qemu/int128: Add int128_geu softfloat: Use mulu64 for mul64To128 softfloat: Use int128.h for some operations softfloat: Tidy a * b + inf return softfloat: Add float_cmask and constants softfloat: Inline float_raise Test split to softfloat-parts.c.inc softfloat: Streamline FloatFmt Test float128_addsub softfloat: Use float_cmask for addsub_floats softfloat: Improve subtraction of equal exponent include/fpu/softfloat-macros.h | 89 ++-- include/fpu/softfloat.h | 5 +- include/qemu/int128.h | 61 ++- fpu/softfloat.c | 802 ++++++++++----------------------- softmmu/physmem.c | 4 +- target/ppc/int_helper.c | 4 +- tests/test-int128.c | 44 +- fpu/softfloat-parts.c.inc | 339 ++++++++++++++ fpu/softfloat-specialize.c.inc | 45 +- 9 files changed, 716 insertions(+), 677 deletions(-) create mode 100644 fpu/softfloat-parts.c.inc -- 2.25.1