[libclc] 191/291: math: Add acos implementation

[Andreas Beckmann]

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anbe pushed a commit to branch master
in repository libclc.

commit 2b6cbed810655a8e3cd2683f9475a2c66c8f26c6
Author: Aaron Watry <awatry at gmail.com>
Date:   Wed Sep 10 15:43:29 2014 +0000

    math: Add acos implementation
    
    Passes the tests that were submitted to the piglit list
    
    Tested on R600 (Pitcairn)
    
    Signed-off-by: Aaron Watry <awatry at gmail.com>
    Reviewed-by: Jan Vesely <jan.vesely at rutgers.edu>
    
    git-svn-id: https://llvm.org/svn/llvm-project/libclc/trunk@217509 91177308-0d34-0410-b5e6-96231b3b80d8
---
 generic/include/clc/clc.h         |  1 +
 generic/include/clc/math/acos.h   |  2 ++
 generic/include/clc/math/acos.inc |  1 +
 generic/lib/SOURCES               |  1 +
 generic/lib/math/acos.cl          |  8 ++++++++
 generic/lib/math/acos.inc         | 21 +++++++++++++++++++++
 6 files changed, 34 insertions(+)

diff --git a/generic/include/clc/clc.h b/generic/include/clc/clc.h
index 45b107c..0fc8530 100644
--- a/generic/include/clc/clc.h
+++ b/generic/include/clc/clc.h
@@ -32,6 +32,7 @@
 #include <clc/workitem/get_group_id.h>
 
 /* 6.11.2 Math Functions */
+#include <clc/math/acos.h>
 #include <clc/math/atan.h>
 #include <clc/math/atan2.h>
 #include <clc/math/copysign.h>
diff --git a/generic/include/clc/math/acos.h b/generic/include/clc/math/acos.h
new file mode 100644
index 0000000..e753dee
--- /dev/null
+++ b/generic/include/clc/math/acos.h
@@ -0,0 +1,2 @@
+#define __CLC_BODY <clc/math/acos.inc>
+#include <clc/math/gentype.inc>
diff --git a/generic/include/clc/math/acos.inc b/generic/include/clc/math/acos.inc
new file mode 100644
index 0000000..4ca8c75
--- /dev/null
+++ b/generic/include/clc/math/acos.inc
@@ -0,0 +1 @@
+_CLC_OVERLOAD _CLC_DECL __CLC_GENTYPE acos(__CLC_GENTYPE x);
diff --git a/generic/lib/SOURCES b/generic/lib/SOURCES
index 22fc1fb..577671c 100644
--- a/generic/lib/SOURCES
+++ b/generic/lib/SOURCES
@@ -29,6 +29,7 @@ integer/sub_sat.cl
 integer/sub_sat_if.ll
 integer/sub_sat_impl.ll
 integer/upsample.cl
+math/acos.cl
 math/atan.cl
 math/atan2.cl
 math/copysign.cl
diff --git a/generic/lib/math/acos.cl b/generic/lib/math/acos.cl
new file mode 100644
index 0000000..3ce9655
--- /dev/null
+++ b/generic/lib/math/acos.cl
@@ -0,0 +1,8 @@
+#include <clc/clc.h>
+
+#ifdef cl_khr_fp64
+#pragma OPENCL EXTENSION cl_khr_fp64 : enable
+#endif
+
+#define __CLC_BODY <acos.inc>
+#include <clc/math/gentype.inc>
diff --git a/generic/lib/math/acos.inc b/generic/lib/math/acos.inc
new file mode 100644
index 0000000..8612415
--- /dev/null
+++ b/generic/lib/math/acos.inc
@@ -0,0 +1,21 @@
+/*
+ * There are multiple formulas for calculating arccosine of x:
+ * 1) acos(x) = (1/2*pi) + i * ln(i*x + sqrt(1-x^2)) (notice the 'i'...)
+ * 2) acos(x) = pi/2 + asin(-x) (asin isn't implemented yet)
+ * 3) acos(x) = pi/2 - asin(x) (ditto)
+ * 4) acos(x) = 2*atan2(sqrt(1-x), sqrt(1+x))
+ * 5) acos(x) = pi/2 - atan2(x, ( sqrt(1-x^2) ) )
+ *
+ * Options 1-3 are not currently usable, #5 generates more concise radeonsi
+ * bitcode and assembly than #4 (134 vs 132 instructions on radeonsi), but
+ * precision of #4 may be better.
+ */
+
+_CLC_OVERLOAD _CLC_DEF __CLC_GENTYPE acos(__CLC_GENTYPE x) {
+  return (
+    (__CLC_GENTYPE) 2.0 * atan2(
+      sqrt((__CLC_GENTYPE) 1.0 - x),
+      sqrt((__CLC_GENTYPE) 1.0 + x)
+    )
+  );
+}

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