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Message-Id: <20240613080717.546252-1-mzh@mzh.io> Date: Thu, 13 Jun 2024 16:07:17 +0800 From: Meng Zhuo <mzh@....io> To: musl@...ts.openwall.com Subject: [PATCH v4] math: add riscv64 round/roundf --- v3 -> v4: * add fabs(f) to avoild overflow. * add comment on -0 copysign Thanks for review! How to implement "single cmp+branch on the bit representation of x"? I've tried Google bit hacks of it. Could you give some tip or refs? --- src/math/riscv64/round.c | 21 +++++++++++++++++++++ src/math/riscv64/roundf.c | 21 +++++++++++++++++++++ 2 files changed, 42 insertions(+) create mode 100644 src/math/riscv64/round.c create mode 100644 src/math/riscv64/roundf.c diff --git a/src/math/riscv64/round.c b/src/math/riscv64/round.c new file mode 100644 index 00000000..7d7ade9d --- /dev/null +++ b/src/math/riscv64/round.c @@ -0,0 +1,21 @@ +#include <math.h> + +#if __riscv_flen >= 64 + +double round(double x) +{ + if (!isfinite(x) || fabs(x) >= 0x1p52) return x; + double tmp; + long long n; + __asm__ ("fcvt.l.d %0, %1, rmm" : "=r"(n) : "f"(x)); + __asm__ ("fcvt.d.l %0, %1" : "=f"(tmp) : "r"(n)); + // the sign bit is only copied to handle round(-0.0) + __asm__ ("fsgnj.d %0, %1, %2" : "=f"(x) : "f"(tmp), "f"(x)); + return x; +} + +#else + +#include "../round.c" + +#endif diff --git a/src/math/riscv64/roundf.c b/src/math/riscv64/roundf.c new file mode 100644 index 00000000..be588574 --- /dev/null +++ b/src/math/riscv64/roundf.c @@ -0,0 +1,21 @@ +#include <math.h> + +#if __riscv_flen >= 32 + +float roundf(float x) +{ + if (!isfinite(x) || fabsf(x) >= 0x1p23) return x; + float tmp; + long n; + __asm__ ("fcvt.w.s %0, %1, rmm" : "=r"(n) : "f"(x)); + __asm__ ("fcvt.s.w %0, %1" : "=f"(tmp) : "r"(n)); + // the sign bit is only copied to handle round(-0.0) + __asm__ ("fsgnj.s %0, %1, %2" : "=f"(x) : "f"(tmp), "f"(x)); + return x; +} + +#else + +#include "../roundf.c" + +#endif -- 2.39.2
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