Merge Filament's math library

This math library was derived from Android's and is API compatible.
It adds new useful types (quat and half) as well as many missing
functions and optimizations.

The half type (fp16) is going to be used for HDR/color management.

Test: mat_test, quat_test, half_test and vec_test

Change-Id: I4c61efb085d6aa2cf5b43cdd194719b3e855aa9b
diff --git a/include/ui/TMatHelpers.h b/include/ui/TMatHelpers.h
index a6aadca..9daca08 100644
--- a/include/ui/TMatHelpers.h
+++ b/include/ui/TMatHelpers.h
@@ -14,25 +14,35 @@
  * limitations under the License.
  */
 
-#ifndef TMAT_IMPLEMENTATION
-#error "Don't include TMatHelpers.h directly. use ui/mat*.h instead"
-#else
-#undef TMAT_IMPLEMENTATION
-#endif
+#ifndef UI_TMATHELPERS_H_
+#define UI_TMATHELPERS_H_
 
-
-#ifndef UI_TMAT_HELPERS_H
-#define UI_TMAT_HELPERS_H
-
+#include <math.h>
 #include <stdint.h>
 #include <sys/types.h>
-#include <math.h>
-#include <utils/Debug.h>
-#include <utils/String8.h>
+
+#include <cmath>
+#include <exception>
+#include <iomanip>
+#include <stdexcept>
+
+#include <ui/quat.h>
+#include <ui/TVecHelpers.h>
+
+#include  <utils/String8.h>
+
+#ifdef __cplusplus
+#   define LIKELY( exp )    (__builtin_expect( !!(exp), true ))
+#   define UNLIKELY( exp )  (__builtin_expect( !!(exp), false ))
+#else
+#   define LIKELY( exp )    (__builtin_expect( !!(exp), 1 ))
+#   define UNLIKELY( exp )  (__builtin_expect( !!(exp), 0 ))
+#endif
 
 #define PURE __attribute__((pure))
 
 namespace android {
+namespace details {
 // -------------------------------------------------------------------------------------
 
 /*
@@ -48,63 +58,177 @@
 
 namespace matrix {
 
-inline int     PURE transpose(int v)    { return v; }
-inline float   PURE transpose(float v)  { return v; }
-inline double  PURE transpose(double v) { return v; }
+inline constexpr int     transpose(int v)    { return v; }
+inline constexpr float   transpose(float v)  { return v; }
+inline constexpr double  transpose(double v) { return v; }
 
-inline int     PURE trace(int v)    { return v; }
-inline float   PURE trace(float v)  { return v; }
-inline double  PURE trace(double v) { return v; }
+inline constexpr int     trace(int v)    { return v; }
+inline constexpr float   trace(float v)  { return v; }
+inline constexpr double  trace(double v) { return v; }
 
+/*
+ * Matrix inversion
+ */
 template<typename MATRIX>
-MATRIX PURE inverse(const MATRIX& src) {
-
-    COMPILE_TIME_ASSERT_FUNCTION_SCOPE( MATRIX::COL_SIZE == MATRIX::ROW_SIZE );
-
-    typename MATRIX::value_type t;
-    const size_t N = MATRIX::col_size();
-    size_t swap;
+MATRIX PURE gaussJordanInverse(const MATRIX& src) {
+    typedef typename MATRIX::value_type T;
+    static constexpr unsigned int N = MATRIX::NUM_ROWS;
     MATRIX tmp(src);
-    MATRIX inverse(1);
+    MATRIX inverted(1);
 
-    for (size_t i=0 ; i<N ; i++) {
-        // look for largest element in column
-        swap = i;
-        for (size_t j=i+1 ; j<N ; j++) {
-            if (fabs(tmp[j][i]) > fabs(tmp[i][i])) {
+    for (size_t i = 0; i < N; ++i) {
+        // look for largest element in i'th column
+        size_t swap = i;
+        T t = std::abs(tmp[i][i]);
+        for (size_t j = i + 1; j < N; ++j) {
+            const T t2 = std::abs(tmp[j][i]);
+            if (t2 > t) {
                 swap = j;
+                t = t2;
             }
         }
 
         if (swap != i) {
-            /* swap rows. */
-            for (size_t k=0 ; k<N ; k++) {
-                t = tmp[i][k];
-                tmp[i][k] = tmp[swap][k];
-                tmp[swap][k] = t;
-
-                t = inverse[i][k];
-                inverse[i][k] = inverse[swap][k];
-                inverse[swap][k] = t;
-            }
+            // swap columns.
+            std::swap(tmp[i], tmp[swap]);
+            std::swap(inverted[i], inverted[swap]);
         }
 
-        t = 1 / tmp[i][i];
-        for (size_t k=0 ; k<N ; k++) {
-            tmp[i][k] *= t;
-            inverse[i][k] *= t;
+        const T denom(tmp[i][i]);
+        for (size_t k = 0; k < N; ++k) {
+            tmp[i][k] /= denom;
+            inverted[i][k] /= denom;
         }
-        for (size_t j=0 ; j<N ; j++) {
+
+        // Factor out the lower triangle
+        for (size_t j = 0; j < N; ++j) {
             if (j != i) {
-                t = tmp[j][i];
-                for (size_t k=0 ; k<N ; k++) {
+                const T t = tmp[j][i];
+                for (size_t k = 0; k < N; ++k) {
                     tmp[j][k] -= tmp[i][k] * t;
-                    inverse[j][k] -= inverse[i][k] * t;
+                    inverted[j][k] -= inverted[i][k] * t;
                 }
             }
         }
     }
-    return inverse;
+
+    return inverted;
+}
+
+
+//------------------------------------------------------------------------------
+// 2x2 matrix inverse is easy.
+template <typename MATRIX>
+MATRIX PURE fastInverse2(const MATRIX& x) {
+    typedef typename MATRIX::value_type T;
+
+    // Assuming the input matrix is:
+    // | a b |
+    // | c d |
+    //
+    // The analytic inverse is
+    // | d -b |
+    // | -c a | / (a d - b c)
+    //
+    // Importantly, our matrices are column-major!
+
+    MATRIX inverted(MATRIX::NO_INIT);
+
+    const T a = x[0][0];
+    const T c = x[0][1];
+    const T b = x[1][0];
+    const T d = x[1][1];
+
+    const T det((a * d) - (b * c));
+    inverted[0][0] =  d / det;
+    inverted[0][1] = -c / det;
+    inverted[1][0] = -b / det;
+    inverted[1][1] =  a / det;
+    return inverted;
+}
+
+
+//------------------------------------------------------------------------------
+// From the Wikipedia article on matrix inversion's section on fast 3x3
+// matrix inversion:
+// http://en.wikipedia.org/wiki/Invertible_matrix#Inversion_of_3.C3.973_matrices
+template <typename MATRIX>
+MATRIX PURE fastInverse3(const MATRIX& x) {
+    typedef typename MATRIX::value_type T;
+
+    // Assuming the input matrix is:
+    // | a b c |
+    // | d e f |
+    // | g h i |
+    //
+    // The analytic inverse is
+    // | A B C |^T
+    // | D E F |
+    // | G H I | / determinant
+    //
+    // Which is
+    // | A D G |
+    // | B E H |
+    // | C F I | / determinant
+    //
+    // Where:
+    // A = (ei - fh), B = (fg - di), C = (dh - eg)
+    // D = (ch - bi), E = (ai - cg), F = (bg - ah)
+    // G = (bf - ce), H = (cd - af), I = (ae - bd)
+    //
+    // and the determinant is a*A + b*B + c*C (The rule of Sarrus)
+    //
+    // Importantly, our matrices are column-major!
+
+    MATRIX inverted(MATRIX::NO_INIT);
+
+    const T a = x[0][0];
+    const T b = x[1][0];
+    const T c = x[2][0];
+    const T d = x[0][1];
+    const T e = x[1][1];
+    const T f = x[2][1];
+    const T g = x[0][2];
+    const T h = x[1][2];
+    const T i = x[2][2];
+
+    // Do the full analytic inverse
+    const T A = e * i - f * h;
+    const T B = f * g - d * i;
+    const T C = d * h - e * g;
+    inverted[0][0] = A;                 // A
+    inverted[0][1] = B;                 // B
+    inverted[0][2] = C;                 // C
+    inverted[1][0] = c * h - b * i;     // D
+    inverted[1][1] = a * i - c * g;     // E
+    inverted[1][2] = b * g - a * h;     // F
+    inverted[2][0] = b * f - c * e;     // G
+    inverted[2][1] = c * d - a * f;     // H
+    inverted[2][2] = a * e - b * d;     // I
+
+    const T det(a * A + b * B + c * C);
+    for (size_t col = 0; col < 3; ++col) {
+        for (size_t row = 0; row < 3; ++row) {
+            inverted[col][row] /= det;
+        }
+    }
+
+    return inverted;
+}
+
+
+/**
+ * Inversion function which switches on the matrix size.
+ * @warning This function assumes the matrix is invertible. The result is
+ * undefined if it is not. It is the responsibility of the caller to
+ * make sure the matrix is not singular.
+ */
+template <typename MATRIX>
+inline constexpr MATRIX PURE inverse(const MATRIX& matrix) {
+    static_assert(MATRIX::NUM_ROWS == MATRIX::NUM_COLS, "only square matrices can be inverted");
+    return (MATRIX::NUM_ROWS == 2) ? fastInverse2<MATRIX>(matrix) :
+          ((MATRIX::NUM_ROWS == 3) ? fastInverse3<MATRIX>(matrix) :
+                    gaussJordanInverse<MATRIX>(matrix));
 }
 
 template<typename MATRIX_R, typename MATRIX_A, typename MATRIX_B>
@@ -114,13 +238,16 @@
     //  rhs : C columns, D rows
     //  res : C columns, R rows
 
-    COMPILE_TIME_ASSERT_FUNCTION_SCOPE( MATRIX_A::ROW_SIZE == MATRIX_B::COL_SIZE );
-    COMPILE_TIME_ASSERT_FUNCTION_SCOPE( MATRIX_R::ROW_SIZE == MATRIX_B::ROW_SIZE );
-    COMPILE_TIME_ASSERT_FUNCTION_SCOPE( MATRIX_R::COL_SIZE == MATRIX_A::COL_SIZE );
+    static_assert(MATRIX_A::NUM_COLS == MATRIX_B::NUM_ROWS,
+            "matrices can't be multiplied. invalid dimensions.");
+    static_assert(MATRIX_R::NUM_COLS == MATRIX_B::NUM_COLS,
+            "invalid dimension of matrix multiply result.");
+    static_assert(MATRIX_R::NUM_ROWS == MATRIX_A::NUM_ROWS,
+            "invalid dimension of matrix multiply result.");
 
     MATRIX_R res(MATRIX_R::NO_INIT);
-    for (size_t r=0 ; r<MATRIX_R::row_size() ; r++) {
-        res[r] = lhs * rhs[r];
+    for (size_t col = 0; col < MATRIX_R::NUM_COLS; ++col) {
+        res[col] = lhs * rhs[col];
     }
     return res;
 }
@@ -129,40 +256,88 @@
 template <typename MATRIX>
 MATRIX PURE transpose(const MATRIX& m) {
     // for now we only handle square matrix transpose
-    COMPILE_TIME_ASSERT_FUNCTION_SCOPE( MATRIX::ROW_SIZE == MATRIX::COL_SIZE );
+    static_assert(MATRIX::NUM_COLS == MATRIX::NUM_ROWS, "transpose only supports square matrices");
     MATRIX result(MATRIX::NO_INIT);
-    for (size_t r=0 ; r<MATRIX::row_size() ; r++)
-        for (size_t c=0 ; c<MATRIX::col_size() ; c++)
-            result[c][r] = transpose(m[r][c]);
+    for (size_t col = 0; col < MATRIX::NUM_COLS; ++col) {
+        for (size_t row = 0; row < MATRIX::NUM_ROWS; ++row) {
+            result[col][row] = transpose(m[row][col]);
+        }
+    }
     return result;
 }
 
 // trace. this handles matrices of matrices
 template <typename MATRIX>
 typename MATRIX::value_type PURE trace(const MATRIX& m) {
-    COMPILE_TIME_ASSERT_FUNCTION_SCOPE( MATRIX::ROW_SIZE == MATRIX::COL_SIZE );
+    static_assert(MATRIX::NUM_COLS == MATRIX::NUM_ROWS, "trace only defined for square matrices");
     typename MATRIX::value_type result(0);
-    for (size_t r=0 ; r<MATRIX::row_size() ; r++)
-        result += trace(m[r][r]);
+    for (size_t col = 0; col < MATRIX::NUM_COLS; ++col) {
+        result += trace(m[col][col]);
+    }
     return result;
 }
 
-// trace. this handles matrices of matrices
+// diag. this handles matrices of matrices
 template <typename MATRIX>
 typename MATRIX::col_type PURE diag(const MATRIX& m) {
-    COMPILE_TIME_ASSERT_FUNCTION_SCOPE( MATRIX::ROW_SIZE == MATRIX::COL_SIZE );
+    static_assert(MATRIX::NUM_COLS == MATRIX::NUM_ROWS, "diag only defined for square matrices");
     typename MATRIX::col_type result(MATRIX::col_type::NO_INIT);
-    for (size_t r=0 ; r<MATRIX::row_size() ; r++)
-        result[r] = m[r][r];
+    for (size_t col = 0; col < MATRIX::NUM_COLS; ++col) {
+        result[col] = m[col][col];
+    }
     return result;
 }
 
+//------------------------------------------------------------------------------
+// This is taken from the Imath MatrixAlgo code, and is identical to Eigen.
+template <typename MATRIX>
+TQuaternion<typename MATRIX::value_type> extractQuat(const MATRIX& mat) {
+    typedef typename MATRIX::value_type T;
+
+    TQuaternion<T> quat(TQuaternion<T>::NO_INIT);
+
+    // Compute the trace to see if it is positive or not.
+    const T trace = mat[0][0] + mat[1][1] + mat[2][2];
+
+    // check the sign of the trace
+    if (LIKELY(trace > 0)) {
+        // trace is positive
+        T s = std::sqrt(trace + 1);
+        quat.w = T(0.5) * s;
+        s = T(0.5) / s;
+        quat.x = (mat[1][2] - mat[2][1]) * s;
+        quat.y = (mat[2][0] - mat[0][2]) * s;
+        quat.z = (mat[0][1] - mat[1][0]) * s;
+    } else {
+        // trace is negative
+
+        // Find the index of the greatest diagonal
+        size_t i = 0;
+        if (mat[1][1] > mat[0][0]) { i = 1; }
+        if (mat[2][2] > mat[i][i]) { i = 2; }
+
+        // Get the next indices: (n+1)%3
+        static constexpr size_t next_ijk[3] = { 1, 2, 0 };
+        size_t j = next_ijk[i];
+        size_t k = next_ijk[j];
+        T s = std::sqrt((mat[i][i] - (mat[j][j] + mat[k][k])) + 1);
+        quat[i] = T(0.5) * s;
+        if (s != 0) {
+            s = T(0.5) / s;
+        }
+        quat.w  = (mat[j][k] - mat[k][j]) * s;
+        quat[j] = (mat[i][j] + mat[j][i]) * s;
+        quat[k] = (mat[i][k] + mat[k][i]) * s;
+    }
+    return quat;
+}
+
 template <typename MATRIX>
 String8 asString(const MATRIX& m) {
     String8 s;
-    for (size_t c=0 ; c<MATRIX::col_size() ; c++) {
+    for (size_t c = 0; c < MATRIX::col_size(); c++) {
         s.append("|  ");
-        for (size_t r=0 ; r<MATRIX::row_size() ; r++) {
+        for (size_t r = 0; r < MATRIX::row_size(); r++) {
             s.appendFormat("%7.2f  ", m[r][c]);
         }
         s.append("|\n");
@@ -170,7 +345,7 @@
     return s;
 }
 
-}; // namespace matrix
+}  // namespace matrix
 
 // -------------------------------------------------------------------------------------
 
@@ -189,17 +364,25 @@
     // multiply by a scalar
     BASE<T>& operator *= (T v) {
         BASE<T>& lhs(static_cast< BASE<T>& >(*this));
-        for (size_t r=0 ; r<lhs.row_size() ; r++) {
-            lhs[r] *= v;
+        for (size_t col = 0; col < BASE<T>::NUM_COLS; ++col) {
+            lhs[col] *= v;
         }
         return lhs;
     }
 
+    //  matrix *= matrix
+    template<typename U>
+    const BASE<T>& operator *= (const BASE<U>& rhs) {
+        BASE<T>& lhs(static_cast< BASE<T>& >(*this));
+        lhs = matrix::multiply<BASE<T> >(lhs, rhs);
+        return lhs;
+    }
+
     // divide by a scalar
     BASE<T>& operator /= (T v) {
         BASE<T>& lhs(static_cast< BASE<T>& >(*this));
-        for (size_t r=0 ; r<lhs.row_size() ; r++) {
-            lhs[r] /= v;
+        for (size_t col = 0; col < BASE<T>::NUM_COLS; ++col) {
+            lhs[col] /= v;
         }
         return lhs;
     }
@@ -211,7 +394,6 @@
     }
 };
 
-
 /*
  * TMatSquareFunctions implements functions on a matrix of type BASE<T>.
  *
@@ -229,6 +411,7 @@
 template<template<typename U> class BASE, typename T>
 class TMatSquareFunctions {
 public:
+
     /*
      * NOTE: the functions below ARE NOT member methods. They are friend functions
      * with they definition inlined with their declaration. This makes these
@@ -236,22 +419,216 @@
      * is instantiated, at which point they're only templated on the 2nd parameter
      * (the first one, BASE<T> being known).
      */
-    friend BASE<T> PURE inverse(const BASE<T>& m)   { return matrix::inverse(m); }
-    friend BASE<T> PURE transpose(const BASE<T>& m) { return matrix::transpose(m); }
-    friend T       PURE trace(const BASE<T>& m)     { return matrix::trace(m); }
+    friend inline BASE<T> PURE inverse(const BASE<T>& matrix) {
+        return matrix::inverse(matrix);
+    }
+    friend inline constexpr BASE<T> PURE transpose(const BASE<T>& m) {
+        return matrix::transpose(m);
+    }
+    friend inline constexpr T PURE trace(const BASE<T>& m) {
+        return matrix::trace(m);
+    }
 };
 
+template<template<typename U> class BASE, typename T>
+class TMatHelpers {
+public:
+    constexpr inline size_t getColumnSize() const   { return BASE<T>::COL_SIZE; }
+    constexpr inline size_t getRowSize() const      { return BASE<T>::ROW_SIZE; }
+    constexpr inline size_t getColumnCount() const  { return BASE<T>::NUM_COLS; }
+    constexpr inline size_t getRowCount() const     { return BASE<T>::NUM_ROWS; }
+    constexpr inline size_t size()  const           { return BASE<T>::ROW_SIZE; }  // for TVec*<>
+
+    // array access
+    constexpr T const* asArray() const {
+        return &static_cast<BASE<T> const &>(*this)[0][0];
+    }
+
+    // element access
+    inline constexpr T const& operator()(size_t row, size_t col) const {
+        return static_cast<BASE<T> const &>(*this)[col][row];
+    }
+
+    inline T& operator()(size_t row, size_t col) {
+        return static_cast<BASE<T>&>(*this)[col][row];
+    }
+
+    template <typename VEC>
+    static BASE<T> translate(const VEC& t) {
+        BASE<T> r;
+        r[BASE<T>::NUM_COLS-1] = t;
+        return r;
+    }
+
+    template <typename VEC>
+    static constexpr BASE<T> scale(const VEC& s) {
+        return BASE<T>(s);
+    }
+
+    friend inline BASE<T> PURE abs(BASE<T> m) {
+        for (size_t col = 0; col < BASE<T>::NUM_COLS; ++col) {
+            m[col] = abs(m[col]);
+        }
+        return m;
+    }
+};
+
+// functions for 3x3 and 4x4 matrices
+template<template<typename U> class BASE, typename T>
+class TMatTransform {
+public:
+    inline constexpr TMatTransform() {
+        static_assert(BASE<T>::NUM_ROWS == 3 || BASE<T>::NUM_ROWS == 4, "3x3 or 4x4 matrices only");
+    }
+
+    template <typename A, typename VEC>
+    static BASE<T> rotate(A radian, const VEC& about) {
+        BASE<T> r;
+        T c = std::cos(radian);
+        T s = std::sin(radian);
+        if (about.x == 1 && about.y == 0 && about.z == 0) {
+            r[1][1] = c;   r[2][2] = c;
+            r[1][2] = s;   r[2][1] = -s;
+        } else if (about.x == 0 && about.y == 1 && about.z == 0) {
+            r[0][0] = c;   r[2][2] = c;
+            r[2][0] = s;   r[0][2] = -s;
+        } else if (about.x == 0 && about.y == 0 && about.z == 1) {
+            r[0][0] = c;   r[1][1] = c;
+            r[0][1] = s;   r[1][0] = -s;
+        } else {
+            VEC nabout = normalize(about);
+            typename VEC::value_type x = nabout.x;
+            typename VEC::value_type y = nabout.y;
+            typename VEC::value_type z = nabout.z;
+            T nc = 1 - c;
+            T xy = x * y;
+            T yz = y * z;
+            T zx = z * x;
+            T xs = x * s;
+            T ys = y * s;
+            T zs = z * s;
+            r[0][0] = x*x*nc +  c;    r[1][0] =  xy*nc - zs;    r[2][0] =  zx*nc + ys;
+            r[0][1] =  xy*nc + zs;    r[1][1] = y*y*nc +  c;    r[2][1] =  yz*nc - xs;
+            r[0][2] =  zx*nc - ys;    r[1][2] =  yz*nc + xs;    r[2][2] = z*z*nc +  c;
+
+            // Clamp results to -1, 1.
+            for (size_t col = 0; col < 3; ++col) {
+                for (size_t row = 0; row < 3; ++row) {
+                    r[col][row] = std::min(std::max(r[col][row], T(-1)), T(1));
+                }
+            }
+        }
+        return r;
+    }
+
+    /**
+     * Create a matrix from euler angles using YPR around YXZ respectively
+     * @param yaw about Y axis
+     * @param pitch about X axis
+     * @param roll about Z axis
+     */
+    template <
+        typename Y, typename P, typename R,
+        typename = typename std::enable_if<std::is_arithmetic<Y>::value >::type,
+        typename = typename std::enable_if<std::is_arithmetic<P>::value >::type,
+        typename = typename std::enable_if<std::is_arithmetic<R>::value >::type
+    >
+    static BASE<T> eulerYXZ(Y yaw, P pitch, R roll) {
+        return eulerZYX(roll, pitch, yaw);
+    }
+
+    /**
+     * Create a matrix from euler angles using YPR around ZYX respectively
+     * @param roll about X axis
+     * @param pitch about Y axis
+     * @param yaw about Z axis
+     *
+     * The euler angles are applied in ZYX order. i.e: a vector is first rotated
+     * about X (roll) then Y (pitch) and then Z (yaw).
+     */
+    template <
+    typename Y, typename P, typename R,
+    typename = typename std::enable_if<std::is_arithmetic<Y>::value >::type,
+    typename = typename std::enable_if<std::is_arithmetic<P>::value >::type,
+    typename = typename std::enable_if<std::is_arithmetic<R>::value >::type
+    >
+    static BASE<T> eulerZYX(Y yaw, P pitch, R roll) {
+        BASE<T> r;
+        T cy = std::cos(yaw);
+        T sy = std::sin(yaw);
+        T cp = std::cos(pitch);
+        T sp = std::sin(pitch);
+        T cr = std::cos(roll);
+        T sr = std::sin(roll);
+        T cc = cr * cy;
+        T cs = cr * sy;
+        T sc = sr * cy;
+        T ss = sr * sy;
+        r[0][0] = cp * cy;
+        r[0][1] = cp * sy;
+        r[0][2] = -sp;
+        r[1][0] = sp * sc - cs;
+        r[1][1] = sp * ss + cc;
+        r[1][2] = cp * sr;
+        r[2][0] = sp * cc + ss;
+        r[2][1] = sp * cs - sc;
+        r[2][2] = cp * cr;
+
+        // Clamp results to -1, 1.
+        for (size_t col = 0; col < 3; ++col) {
+            for (size_t row = 0; row < 3; ++row) {
+                r[col][row] = std::min(std::max(r[col][row], T(-1)), T(1));
+            }
+        }
+        return r;
+    }
+
+    TQuaternion<T> toQuaternion() const {
+        return matrix::extractQuat(static_cast<const BASE<T>&>(*this));
+    }
+};
+
+
 template <template<typename T> class BASE, typename T>
 class TMatDebug {
 public:
+    friend std::ostream& operator<<(std::ostream& stream, const BASE<T>& m) {
+        for (size_t row = 0; row < BASE<T>::NUM_ROWS; ++row) {
+            if (row != 0) {
+                stream << std::endl;
+            }
+            if (row == 0) {
+                stream << "/ ";
+            } else if (row == BASE<T>::NUM_ROWS-1) {
+                stream << "\\ ";
+            } else {
+                stream << "| ";
+            }
+            for (size_t col = 0; col < BASE<T>::NUM_COLS; ++col) {
+                stream << std::setw(10) << std::to_string(m[col][row]);
+            }
+            if (row == 0) {
+                stream << " \\";
+            } else if (row == BASE<T>::NUM_ROWS-1) {
+                stream << " /";
+            } else {
+                stream << " |";
+            }
+        }
+        return stream;
+    }
+
     String8 asString() const {
-        return matrix::asString( static_cast< const BASE<T>& >(*this) );
+        return matrix::asString(static_cast<const BASE<T>&>(*this));
     }
 };
 
 // -------------------------------------------------------------------------------------
-}; // namespace android
+}  // namespace details
+}  // namespace android
 
+#undef LIKELY
+#undef UNLIKELY
 #undef PURE
 
-#endif /* UI_TMAT_HELPERS_H */
+#endif  // UI_TMATHELPERS_H_