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add cosf16 function
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13 files changed

+232
-4
lines changed

13 files changed

+232
-4
lines changed

‎libc/config/linux/x86_64/entrypoints.txt‎

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@@ -632,6 +632,7 @@ if(LIBC_TYPES_HAS_FLOAT16)
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libc.src.math.canonicalizef16
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libc.src.math.ceilf16
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libc.src.math.copysignf16
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libc.src.math.cosf16
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libc.src.math.coshf16
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libc.src.math.cospif16
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libc.src.math.exp10f16

‎libc/docs/headers/math/index.rst‎

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@@ -276,7 +276,7 @@ Higher Math Functions
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+-----------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+
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| compoundn | | | | | | 7.12.7.2 | F.10.4.2 |
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+-----------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+
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| cos | |check| | |check| | | | | 7.12.4.5 | F.10.1.5 |
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| cos | |check| | |check| | | |check| | | 7.12.4.5 | F.10.1.5 |
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+-----------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+
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| cosh | |check| | | | |check| | | 7.12.5.4 | F.10.2.4 |
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+-----------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+

‎libc/hdrgen/yaml/math.yaml‎

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Original file line numberDiff line numberDiff line change
@@ -200,6 +200,13 @@ functions:
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return_type: float
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arguments:
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- type: float
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- name: cosf16
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standards:
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- stdc
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return_type: _Float16
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arguments:
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- type: _Float16
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guard: LIBC_TYPES_HAS_FLOAT16
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- name: coshf
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standards:
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- stdc

‎libc/src/math/CMakeLists.txt‎

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@@ -89,6 +89,7 @@ add_math_entrypoint_object(copysignf128)
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add_math_entrypoint_object(cos)
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add_math_entrypoint_object(cosf)
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add_math_entrypoint_object(cosf16)
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add_math_entrypoint_object(cosh)
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add_math_entrypoint_object(coshf)

‎libc/src/math/cosf16.h‎

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@@ -0,0 +1,21 @@
1+
//===-- Implementation header for cosf16 ------------------------*- C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4+
// See https://llvm.org/LICENSE.txt for license information.
5+
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
8+
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#ifndef LLVM_LIBC_SRC_MATH_COSF16_H
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#define LLVM_LIBC_SRC_MATH_COSF16_H
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#include "src/__support/macros/config.h"
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#include "src/__support/macros/properties/types.h"
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namespace LIBC_NAMESPACE_DECL {
16+
17+
float16 cosf16(float16 x);
18+
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} // namespace LIBC_NAMESPACE_DECL
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#endif // LLVM_LIBC_SRC_MATH_COSF16_H

‎libc/src/math/generic/CMakeLists.txt‎

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Original file line numberDiff line numberDiff line change
@@ -418,6 +418,25 @@ add_entrypoint_object(
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${libc_opt_high_flag}
419419
)
420420

421+
add_entrypoint_object(
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cosf16
423+
SRCS
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cosf16.cpp
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HDRS
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../cosf16.h
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DEPENDS
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.sincosf16_utils
429+
libc.hdr.errno_macros
430+
libc.hdr.fenv_macros
431+
libc.src.__support.FPUtil.cast
432+
libc.src.__support.FPUtil.fenv_impl
433+
libc.src.__support.FPUtil.fp_bits
434+
libc.src.__support.FPUtil.except_value_utils
435+
libc.src.__support.FPUtil.multiply_add
436+
libc.src.__support.macros.optimization
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libc.src.__support.macros.properties.types
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)
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add_entrypoint_object(
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cospif
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SRCS

‎libc/src/math/generic/cosf16.cpp‎

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@@ -0,0 +1,84 @@
1+
//===-- Half-precision cos(x) function ------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4+
// See https://llvm.org/LICENSE.txt for license information.
5+
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#include "src/math/cosf16.h"
10+
#include "hdr/errno_macros.h"
11+
#include "hdr/fenv_macros.h"
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#include "sincosf16_utils.h"
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#include "src/__support/FPUtil/FEnvImpl.h"
14+
#include "src/__support/FPUtil/FPBits.h"
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#include "src/__support/FPUtil/cast.h"
16+
#include "src/__support/FPUtil/except_value_utils.h"
17+
#include "src/__support/FPUtil/multiply_add.h"
18+
#include "src/__support/macros/optimization.h"
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namespace LIBC_NAMESPACE_DECL {
21+
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constexpr size_t N_EXCEPTS = 4;
23+
24+
constexpr fputil::ExceptValues<float16, N_EXCEPTS> COSF16_EXCEPTS{{
25+
// (input, RZ output, RU offset, RD offset, RN offset)
26+
{0x2b7c, 0x3bfc, 1, 0, 1},
27+
{0x4ac1, 0x38b5, 1, 0, 0},
28+
{0x5c49, 0xb8c6, 0, 1, 0},
29+
{0x7acc, 0xa474, 0, 1, 0},
30+
}};
31+
32+
LLVM_LIBC_FUNCTION(float16, cosf16, (float16 x)) {
33+
using FPBits = fputil::FPBits<float16>;
34+
FPBits xbits(x);
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36+
uint16_t x_u = xbits.uintval();
37+
uint16_t x_abs = x_u & 0x7fff;
38+
float xf = x;
39+
40+
// Range reduction:
41+
// For |x| > pi/32, we perform range reduction as follows:
42+
// Find k and y such that:
43+
// x = (k + y) * pi/32
44+
// k is an integer, |y| < 0.5
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//
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// This is done by performing:
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// k = round(x * 32/pi)
48+
// y = x * 32/pi - k
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//
50+
// Once k and y are computed, we then deduce the answer by the cosine of sum
51+
// formula:
52+
// cos(x) = cos((k + y) * pi/32)
53+
// = cos(k * pi/32) * cos(y * pi/32) -
54+
// sin(k * pi/32) * sin(y * pi/32)
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// Handle exceptional values
57+
58+
if (LIBC_UNLIKELY(x_abs == 0x2b7c || x_abs == 0x4ac1 || x_abs == 0x5c49 ||
59+
x_abs == 0x7acc)) {
60+
if (auto r = COSF16_EXCEPTS.lookup(x_abs); LIBC_UNLIKELY(r.has_value()))
61+
return r.value();
62+
}
63+
64+
if (LIBC_UNLIKELY(x_abs == 0U))
65+
return fputil::cast<float16>(1.0f);
66+
67+
if (xbits.is_inf_or_nan()) {
68+
if (xbits.is_inf()) {
69+
fputil::set_errno_if_required(EDOM);
70+
fputil::raise_except_if_required(FE_INVALID);
71+
}
72+
73+
return x + FPBits::quiet_nan().get_val();
74+
}
75+
76+
float sin_k, cos_k, sin_y, cosm1_y;
77+
sincosf16_eval(xf, sin_k, cos_k, sin_y, cosm1_y);
78+
// Since, cosm1_y = cos_y - 1, therefore:
79+
// cos(x) = cos_k * cosm1_y - sin_k * sin_y
80+
return fputil::cast<float16>(fputil::multiply_add(
81+
cos_k, cosm1_y, fputil::multiply_add(-sin_k, sin_y, cos_k)));
82+
}
83+
84+
} // namespace LIBC_NAMESPACE_DECL

‎libc/src/math/generic/cospif16.cpp‎

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@@ -73,7 +73,7 @@ LLVM_LIBC_FUNCTION(float16, cospif16, (float16 x)) {
7373
return fputil::cast<float16>(0.0f);
7474

7575
// Since, cosm1_y = cos_y - 1, therefore:
76-
// cos(x * pi) = cos_k(cosm1_y) + cos_k - sin_k * sin_y
76+
// cos(x * pi) = cos_k(cosm1_y) + cos_k - sin_k * sin_y
7777
return fputil::cast<float16>(fputil::multiply_add(
7878
cos_k, cosm1_y, fputil::multiply_add(-sin_k, sin_y, cos_k)));
7979
}

‎libc/src/math/generic/sinf16.cpp‎

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@@ -99,8 +99,8 @@ LLVM_LIBC_FUNCTION(float16, sinf16, (float16 x)) {
9999
if (LIBC_UNLIKELY(sin_y == 0 && sin_k == 0))
100100
return FPBits::zero(xbits.sign()).get_val();
101101

102-
// Since, cosm1_y = cos_y - 1, therfore:
103-
// sin(x) = cos_k * sin_y + sin_k + (cosm1_y * sin_k)
102+
// Since, cosm1_y = cos_y - 1, therefore:
103+
// sin(x) = cos_k * sin_y + sin_k + (cosm1_y * sin_k)
104104
return fputil::cast<float16>(fputil::multiply_add(
105105
sin_y, cos_k, fputil::multiply_add(cosm1_y, sin_k, sin_k)));
106106
}

‎libc/test/src/math/CMakeLists.txt‎

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@@ -28,6 +28,17 @@ add_fp_unittest(
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libc.src.__support.FPUtil.fp_bits
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)
3030

31+
add_fp_unittest(
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cosf16_test
33+
NEED_MPFR
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SUITE
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libc-math-unittests
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SRCS
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cosf16_test.cpp
38+
DEPENDS
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libc.src.math.cosf16
40+
)
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3142
add_fp_unittest(
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cospif_test
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NEED_MPFR

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