/*
 * Copyright (C) 2005 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#ifndef ANDROID_GGL_FIXED_H
#define ANDROID_GGL_FIXED_H

#include <math.h>
#include <pixelflinger/pixelflinger.h>

// ----------------------------------------------------------------------------

#define CONST           __attribute__((const))
#define ALWAYS_INLINE   __attribute__((always_inline))

const GGLfixed FIXED_BITS = 16;
const GGLfixed FIXED_EPSILON  = 1;
const GGLfixed FIXED_ONE  = 1L<<FIXED_BITS;
const GGLfixed FIXED_HALF = 1L<<(FIXED_BITS-1);
const GGLfixed FIXED_MIN  = 0x80000000L;
const GGLfixed FIXED_MAX  = 0x7FFFFFFFL;

inline GGLfixed gglIntToFixed(GGLfixed i)       ALWAYS_INLINE ;
inline GGLfixed gglFixedToIntRound(GGLfixed f)  ALWAYS_INLINE ;
inline GGLfixed gglFixedToIntFloor(GGLfixed f)  ALWAYS_INLINE ;
inline GGLfixed gglFixedToIntCeil(GGLfixed f)   ALWAYS_INLINE ;
inline GGLfixed gglFracx(GGLfixed v)            ALWAYS_INLINE ;
inline GGLfixed gglFloorx(GGLfixed v)           ALWAYS_INLINE ;
inline GGLfixed gglCeilx(GGLfixed v)            ALWAYS_INLINE ;
inline GGLfixed gglCenterx(GGLfixed v)          ALWAYS_INLINE ;
inline GGLfixed gglRoundx(GGLfixed v)           ALWAYS_INLINE ;

GGLfixed gglIntToFixed(GGLfixed i) {
    return i<<FIXED_BITS;
}
GGLfixed gglFixedToIntRound(GGLfixed f) {
    return (f + FIXED_HALF)>>FIXED_BITS;
}
GGLfixed gglFixedToIntFloor(GGLfixed f) {
    return f>>FIXED_BITS;
}
GGLfixed gglFixedToIntCeil(GGLfixed f) {
    return (f + ((1<<FIXED_BITS) - 1))>>FIXED_BITS;
}

GGLfixed gglFracx(GGLfixed v) {
    return v & ((1<<FIXED_BITS)-1);
}
GGLfixed gglFloorx(GGLfixed v) {
    return gglFixedToIntFloor(v)<<FIXED_BITS;
}
GGLfixed gglCeilx(GGLfixed v) {
    return gglFixedToIntCeil(v)<<FIXED_BITS;
}
GGLfixed gglCenterx(GGLfixed v) {
    return gglFloorx(v + FIXED_HALF) | FIXED_HALF;
}
GGLfixed gglRoundx(GGLfixed v) {
    return gglFixedToIntRound(v)<<FIXED_BITS;
}

// conversion from (unsigned) int, short, byte to fixed...
#define GGL_B_TO_X(_x)      GGLfixed( ((int32_t(_x)+1)>>1)<<10 )
#define GGL_S_TO_X(_x)      GGLfixed( ((int32_t(_x)+1)>>1)<<2 )
#define GGL_I_TO_X(_x)      GGLfixed( ((int32_t(_x)>>1)+1)>>14 )
#define GGL_UB_TO_X(_x)     GGLfixed(   uint32_t(_x) +      \
                                        (uint32_t(_x)<<8) + \
                                        (uint32_t(_x)>>7) )
#define GGL_US_TO_X(_x)     GGLfixed( (_x) + ((_x)>>15) )
#define GGL_UI_TO_X(_x)     GGLfixed( (((_x)>>1)+1)>>15 )

// ----------------------------------------------------------------------------

GGLfixed gglPowx(GGLfixed x, GGLfixed y) CONST;
GGLfixed gglSqrtx(GGLfixed a) CONST;
GGLfixed gglSqrtRecipx(GGLfixed x) CONST;
GGLfixed gglFastDivx(GGLfixed n, GGLfixed d) CONST;
int32_t gglMulDivi(int32_t a, int32_t b, int32_t c);

int32_t gglRecipQNormalized(int32_t x, int* exponent);
int32_t gglRecipQ(GGLfixed x, int q) CONST;

inline GGLfixed gglRecip(GGLfixed x) CONST;
inline GGLfixed gglRecip(GGLfixed x) {
    return gglRecipQ(x, 16);
}

inline GGLfixed gglRecip28(GGLfixed x) CONST;
int32_t gglRecip28(GGLfixed x) {
    return gglRecipQ(x, 28);
}

// ----------------------------------------------------------------------------

#if defined(__arm__) && !defined(__thumb__)

// inline ARM implementations
inline GGLfixed gglMulx(GGLfixed x, GGLfixed y, int shift) CONST;
inline GGLfixed gglMulx(GGLfixed x, GGLfixed y, int shift) {
    GGLfixed result, t;
    if (__builtin_constant_p(shift)) {
    asm("smull  %[lo], %[hi], %[x], %[y]            \n"
        "movs   %[lo], %[lo], lsr %[rshift]         \n"
        "adc    %[lo], %[lo], %[hi], lsl %[lshift]  \n"
        : [lo]"=r"(result), [hi]"=r"(t), [x]"=r"(x)
        : "%[x]"(x), [y]"r"(y), [lshift] "I"(32-shift), [rshift] "I"(shift)
        : "cc"
        );
    } else {
    asm("smull  %[lo], %[hi], %[x], %[y]            \n"
        "movs   %[lo], %[lo], lsr %[rshift]         \n"
        "adc    %[lo], %[lo], %[hi], lsl %[lshift]  \n"
        : [lo]"=&r"(result), [hi]"=&r"(t), [x]"=&r"(x)
        : "%[x]"(x), [y]"r"(y), [lshift] "r"(32-shift), [rshift] "r"(shift)
        : "cc"
        );
    }
    return result;
}

inline GGLfixed gglMulAddx(GGLfixed x, GGLfixed y, GGLfixed a, int shift) CONST;
inline GGLfixed gglMulAddx(GGLfixed x, GGLfixed y, GGLfixed a, int shift) {
    GGLfixed result, t;
    if (__builtin_constant_p(shift)) {
    asm("smull  %[lo], %[hi], %[x], %[y]            \n"
        "add    %[lo], %[a],  %[lo], lsr %[rshift]  \n"
        "add    %[lo], %[lo], %[hi], lsl %[lshift]  \n"
        : [lo]"=&r"(result), [hi]"=&r"(t), [x]"=&r"(x)
        : "%[x]"(x), [y]"r"(y), [a]"r"(a), [lshift] "I"(32-shift), [rshift] "I"(shift)
        );
    } else {
    asm("smull  %[lo], %[hi], %[x], %[y]            \n"
        "add    %[lo], %[a],  %[lo], lsr %[rshift]  \n"
        "add    %[lo], %[lo], %[hi], lsl %[lshift]  \n"
        : [lo]"=&r"(result), [hi]"=&r"(t), [x]"=&r"(x)
        : "%[x]"(x), [y]"r"(y), [a]"r"(a), [lshift] "r"(32-shift), [rshift] "r"(shift)
        );
    }
    return result;
}

inline GGLfixed gglMulSubx(GGLfixed x, GGLfixed y, GGLfixed a, int shift) CONST;
inline GGLfixed gglMulSubx(GGLfixed x, GGLfixed y, GGLfixed a, int shift) {
    GGLfixed result, t;
    if (__builtin_constant_p(shift)) {
    asm("smull  %[lo], %[hi], %[x], %[y]            \n"
        "rsb    %[lo], %[a],  %[lo], lsr %[rshift]  \n"
        "add    %[lo], %[lo], %[hi], lsl %[lshift]  \n"
        : [lo]"=&r"(result), [hi]"=&r"(t), [x]"=&r"(x)
        : "%[x]"(x), [y]"r"(y), [a]"r"(a), [lshift] "I"(32-shift), [rshift] "I"(shift)
        );
    } else {
    asm("smull  %[lo], %[hi], %[x], %[y]            \n"
        "rsb    %[lo], %[a],  %[lo], lsr %[rshift]  \n"
        "add    %[lo], %[lo], %[hi], lsl %[lshift]  \n"
        : [lo]"=&r"(result), [hi]"=&r"(t), [x]"=&r"(x)
        : "%[x]"(x), [y]"r"(y), [a]"r"(a), [lshift] "r"(32-shift), [rshift] "r"(shift)
        );
    }
    return result;
}

inline int64_t gglMulii(int32_t x, int32_t y) CONST;
inline int64_t gglMulii(int32_t x, int32_t y)
{
    // 64-bits result: r0=low, r1=high
    union {
        struct {
            int32_t lo;
            int32_t hi;
        } s;
        int64_t res;
    };
    asm("smull %0, %1, %2, %3   \n"
        : "=r"(s.lo), "=&r"(s.hi)
        : "%r"(x), "r"(y)
        :
        );
    return res;
}
#elif defined(__mips__) && __mips_isa_rev < 6

/*inline MIPS implementations*/
inline GGLfixed gglMulx(GGLfixed a, GGLfixed b, int shift) CONST;
inline GGLfixed gglMulx(GGLfixed a, GGLfixed b, int shift) {
    GGLfixed result,tmp,tmp1,tmp2;

    if (__builtin_constant_p(shift)) {
        if (shift == 0) {
            asm ("mult %[a], %[b] \t\n"
              "mflo  %[res]   \t\n"
            : [res]"=&r"(result),[tmp]"=&r"(tmp)
            : [a]"r"(a),[b]"r"(b)
            : "%hi","%lo"
            );
        } else if (shift == 32)
        {
            asm ("mult %[a], %[b] \t\n"
            "li  %[tmp],1\t\n"
            "sll  %[tmp],%[tmp],0x1f\t\n"
            "mflo %[res]   \t\n"
            "addu %[tmp1],%[tmp],%[res] \t\n"
            "sltu %[tmp1],%[tmp1],%[tmp]\t\n"   /*obit*/
            "sra %[tmp],%[tmp],0x1f \t\n"
            "mfhi  %[res]   \t\n"
            "addu %[res],%[res],%[tmp]\t\n"
            "addu %[res],%[res],%[tmp1]\t\n"
            : [res]"=&r"(result),[tmp]"=&r"(tmp),[tmp1]"=&r"(tmp1)
            : [a]"r"(a),[b]"r"(b),[shift]"I"(shift)
            : "%hi","%lo"
            );
        } else if ((shift >0) && (shift < 32))
        {
            asm ("mult %[a], %[b] \t\n"
            "li  %[tmp],1 \t\n"
            "sll  %[tmp],%[tmp],%[shiftm1] \t\n"
            "mflo  %[res]   \t\n"
            "addu %[tmp1],%[tmp],%[res] \t\n"
            "sltu %[tmp1],%[tmp1],%[tmp] \t\n"  /*obit?*/
            "addu  %[res],%[res],%[tmp] \t\n"
            "mfhi  %[tmp]   \t\n"
            "addu  %[tmp],%[tmp],%[tmp1] \t\n"
            "sll   %[tmp],%[tmp],%[lshift] \t\n"
            "srl   %[res],%[res],%[rshift]    \t\n"
            "or    %[res],%[res],%[tmp] \t\n"
            : [res]"=&r"(result),[tmp]"=&r"(tmp),[tmp1]"=&r"(tmp1),[tmp2]"=&r"(tmp2)
            : [a]"r"(a),[b]"r"(b),[lshift]"I"(32-shift),[rshift]"I"(shift),[shiftm1]"I"(shift-1)
            : "%hi","%lo"
            );
        } else {
            asm ("mult %[a], %[b] \t\n"
            "li  %[tmp],1 \t\n"
            "sll  %[tmp],%[tmp],%[shiftm1] \t\n"
            "mflo  %[res]   \t\n"
            "addu %[tmp1],%[tmp],%[res] \t\n"
            "sltu %[tmp1],%[tmp1],%[tmp] \t\n"  /*obit?*/
            "sra  %[tmp2],%[tmp],0x1f \t\n"
            "addu  %[res],%[res],%[tmp] \t\n"
            "mfhi  %[tmp]   \t\n"
            "addu  %[tmp],%[tmp],%[tmp2] \t\n"
            "addu  %[tmp],%[tmp],%[tmp1] \t\n"            /*tmp=hi*/
            "srl   %[tmp2],%[res],%[rshift]    \t\n"
            "srav  %[res], %[tmp],%[rshift]\t\n"
            "sll   %[tmp],%[tmp],1 \t\n"
            "sll   %[tmp],%[tmp],%[norbits] \t\n"
            "or    %[tmp],%[tmp],%[tmp2] \t\n"
            "movz  %[res],%[tmp],%[bit5] \t\n"
            : [res]"=&r"(result),[tmp]"=&r"(tmp),[tmp1]"=&r"(tmp1),[tmp2]"=&r"(tmp2)
            : [a]"r"(a),[b]"r"(b),[norbits]"I"(~(shift)),[rshift]"I"(shift),[shiftm1] "I"(shift-1),[bit5]"I"(shift & 0x20)
            : "%hi","%lo"
            );
        }
    } else {
        asm ("mult %[a], %[b] \t\n"
        "li  %[tmp],1 \t\n"
        "sll  %[tmp],%[tmp],%[shiftm1] \t\n"
        "mflo  %[res]   \t\n"
        "addu %[tmp1],%[tmp],%[res] \t\n"
        "sltu %[tmp1],%[tmp1],%[tmp] \t\n"  /*obit?*/
        "sra  %[tmp2],%[tmp],0x1f \t\n"
        "addu  %[res],%[res],%[tmp] \t\n"
        "mfhi  %[tmp]   \t\n"
        "addu  %[tmp],%[tmp],%[tmp2] \t\n"
        "addu  %[tmp],%[tmp],%[tmp1] \t\n"            /*tmp=hi*/
        "srl   %[tmp2],%[res],%[rshift]    \t\n"
        "srav  %[res], %[tmp],%[rshift]\t\n"
        "sll   %[tmp],%[tmp],1 \t\n"
        "sll   %[tmp],%[tmp],%[norbits] \t\n"
        "or    %[tmp],%[tmp],%[tmp2] \t\n"
        "movz  %[res],%[tmp],%[bit5] \t\n"
         : [res]"=&r"(result),[tmp]"=&r"(tmp),[tmp1]"=&r"(tmp1),[tmp2]"=&r"(tmp2)
         : [a]"r"(a),[b]"r"(b),[norbits]"r"(~(shift)),[rshift] "r"(shift),[shiftm1]"r"(shift-1),[bit5] "r"(shift & 0x20)
         : "%hi","%lo"
         );
        }

        return result;
}

inline GGLfixed gglMulAddx(GGLfixed a, GGLfixed b, GGLfixed c, int shift) CONST;
inline GGLfixed gglMulAddx(GGLfixed a, GGLfixed b, GGLfixed c, int shift) {
    GGLfixed result,t,tmp1,tmp2;

    if (__builtin_constant_p(shift)) {
        if (shift == 0) {
                 asm ("mult %[a], %[b] \t\n"
                 "mflo  %[lo]   \t\n"
                 "addu  %[lo],%[lo],%[c]    \t\n"
                 : [lo]"=&r"(result)
                 : [a]"r"(a),[b]"r"(b),[c]"r"(c)
                 : "%hi","%lo"
                 );
                } else if (shift == 32) {
                    asm ("mult %[a], %[b] \t\n"
                    "mfhi  %[lo]   \t\n"
                    "addu  %[lo],%[lo],%[c]    \t\n"
                    : [lo]"=&r"(result)
                    : [a]"r"(a),[b]"r"(b),[c]"r"(c)
                    : "%hi","%lo"
                    );
                } else if ((shift>0) && (shift<32)) {
                    asm ("mult %[a], %[b] \t\n"
                    "mflo  %[res]   \t\n"
                    "mfhi  %[t]   \t\n"
                    "srl   %[res],%[res],%[rshift]    \t\n"
                    "sll   %[t],%[t],%[lshift]     \t\n"
                    "or  %[res],%[res],%[t]    \t\n"
                    "addu  %[res],%[res],%[c]    \t\n"
                    : [res]"=&r"(result),[t]"=&r"(t)
                    : [a]"r"(a),[b]"r"(b),[c]"r"(c),[lshift]"I"(32-shift),[rshift]"I"(shift)
                    : "%hi","%lo"
                    );
                } else {
                    asm ("mult %[a], %[b] \t\n"
                    "nor %[tmp1],$zero,%[shift]\t\n"
                    "mflo  %[res]   \t\n"
                    "mfhi  %[t]   \t\n"
                    "srl   %[res],%[res],%[shift]    \t\n"
                    "sll   %[tmp2],%[t],1     \t\n"
                    "sllv  %[tmp2],%[tmp2],%[tmp1]     \t\n"
                    "or  %[tmp1],%[tmp2],%[res]    \t\n"
                    "srav  %[res],%[t],%[shift]     \t\n"
                    "andi %[tmp2],%[shift],0x20\t\n"
                    "movz %[res],%[tmp1],%[tmp2]\t\n"
                    "addu  %[res],%[res],%[c]    \t\n"
                    : [res]"=&r"(result),[t]"=&r"(t),[tmp1]"=&r"(tmp1),[tmp2]"=&r"(tmp2)
                    : [a]"r"(a),[b]"r"(b),[c]"r"(c),[shift]"I"(shift)
                    : "%hi","%lo"
                    );
                }
            } else {
                asm ("mult %[a], %[b] \t\n"
                "nor %[tmp1],$zero,%[shift]\t\n"
                "mflo  %[res]   \t\n"
                "mfhi  %[t]   \t\n"
                "srl   %[res],%[res],%[shift]    \t\n"
                "sll   %[tmp2],%[t],1     \t\n"
                "sllv  %[tmp2],%[tmp2],%[tmp1]     \t\n"
                "or  %[tmp1],%[tmp2],%[res]    \t\n"
                "srav  %[res],%[t],%[shift]     \t\n"
                "andi %[tmp2],%[shift],0x20\t\n"
                "movz %[res],%[tmp1],%[tmp2]\t\n"
                "addu  %[res],%[res],%[c]    \t\n"
                : [res]"=&r"(result),[t]"=&r"(t),[tmp1]"=&r"(tmp1),[tmp2]"=&r"(tmp2)
                : [a]"r"(a),[b]"r"(b),[c]"r"(c),[shift]"r"(shift)
                : "%hi","%lo"
                );
            }
            return result;
}

inline GGLfixed gglMulSubx(GGLfixed a, GGLfixed b, GGLfixed c, int shift) CONST;
inline GGLfixed gglMulSubx(GGLfixed a, GGLfixed b, GGLfixed c, int shift) {
    GGLfixed result,t,tmp1,tmp2;

    if (__builtin_constant_p(shift)) {
        if (shift == 0) {
                 asm ("mult %[a], %[b] \t\n"
                 "mflo  %[lo]   \t\n"
                 "subu  %[lo],%[lo],%[c]    \t\n"
                 : [lo]"=&r"(result)
                 : [a]"r"(a),[b]"r"(b),[c]"r"(c)
                 : "%hi","%lo"
                 );
                } else if (shift == 32) {
                    asm ("mult %[a], %[b] \t\n"
                    "mfhi  %[lo]   \t\n"
                    "subu  %[lo],%[lo],%[c]    \t\n"
                    : [lo]"=&r"(result)
                    : [a]"r"(a),[b]"r"(b),[c]"r"(c)
                    : "%hi","%lo"
                    );
                } else if ((shift>0) && (shift<32)) {
                    asm ("mult %[a], %[b] \t\n"
                    "mflo  %[res]   \t\n"
                    "mfhi  %[t]   \t\n"
                    "srl   %[res],%[res],%[rshift]    \t\n"
                    "sll   %[t],%[t],%[lshift]     \t\n"
                    "or  %[res],%[res],%[t]    \t\n"
                    "subu  %[res],%[res],%[c]    \t\n"
                    : [res]"=&r"(result),[t]"=&r"(t)
                    : [a]"r"(a),[b]"r"(b),[c]"r"(c),[lshift]"I"(32-shift),[rshift]"I"(shift)
                    : "%hi","%lo"
                    );
                } else {
                    asm ("mult %[a], %[b] \t\n"
                    "nor %[tmp1],$zero,%[shift]\t\n"
                     "mflo  %[res]   \t\n"
                     "mfhi  %[t]   \t\n"
                     "srl   %[res],%[res],%[shift]    \t\n"
                     "sll   %[tmp2],%[t],1     \t\n"
                     "sllv  %[tmp2],%[tmp2],%[tmp1]     \t\n"
                     "or  %[tmp1],%[tmp2],%[res]    \t\n"
                     "srav  %[res],%[t],%[shift]     \t\n"
                     "andi %[tmp2],%[shift],0x20\t\n"
                     "movz %[res],%[tmp1],%[tmp2]\t\n"
                     "subu  %[res],%[res],%[c]    \t\n"
                     : [res]"=&r"(result),[t]"=&r"(t),[tmp1]"=&r"(tmp1),[tmp2]"=&r"(tmp2)
                     : [a]"r"(a),[b]"r"(b),[c]"r"(c),[shift]"I"(shift)
                     : "%hi","%lo"
                     );
                    }
                } else {
                asm ("mult %[a], %[b] \t\n"
                "nor %[tmp1],$zero,%[shift]\t\n"
                "mflo  %[res]   \t\n"
                "mfhi  %[t]   \t\n"
                "srl   %[res],%[res],%[shift]    \t\n"
                "sll   %[tmp2],%[t],1     \t\n"
                "sllv  %[tmp2],%[tmp2],%[tmp1]     \t\n"
                "or  %[tmp1],%[tmp2],%[res]    \t\n"
                "srav  %[res],%[t],%[shift]     \t\n"
                "andi %[tmp2],%[shift],0x20\t\n"
                "movz %[res],%[tmp1],%[tmp2]\t\n"
                "subu  %[res],%[res],%[c]    \t\n"
                : [res]"=&r"(result),[t]"=&r"(t),[tmp1]"=&r"(tmp1),[tmp2]"=&r"(tmp2)
                : [a]"r"(a),[b]"r"(b),[c]"r"(c),[shift]"r"(shift)
                : "%hi","%lo"
                );
            }
    return result;
}

inline int64_t gglMulii(int32_t x, int32_t y) CONST;
inline int64_t gglMulii(int32_t x, int32_t y) {
    union {
        struct {
#if defined(__MIPSEL__)
            int32_t lo;
            int32_t hi;
#elif defined(__MIPSEB__)
            int32_t hi;
            int32_t lo;
#endif
        } s;
        int64_t res;
    }u;
    asm("mult %2, %3 \t\n"
        "mfhi %1   \t\n"
        "mflo %0   \t\n"
        : "=r"(u.s.lo), "=&r"(u.s.hi)
        : "%r"(x), "r"(y)
	: "%hi","%lo"
        );
    return u.res;
}

#elif defined(__aarch64__)

// inline AArch64 implementations

inline GGLfixed gglMulx(GGLfixed x, GGLfixed y, int shift) CONST;
inline GGLfixed gglMulx(GGLfixed x, GGLfixed y, int shift)
{
    GGLfixed result;
    GGLfixed round;

    asm("mov    %x[round], #1                        \n"
        "lsl    %x[round], %x[round], %x[shift]      \n"
        "lsr    %x[round], %x[round], #1             \n"
        "smaddl %x[result], %w[x], %w[y],%x[round]   \n"
        "lsr    %x[result], %x[result], %x[shift]    \n"
        : [round]"=&r"(round), [result]"=&r"(result) \
        : [x]"r"(x), [y]"r"(y), [shift] "r"(shift)   \
        :
       );
    return result;
}
inline GGLfixed gglMulAddx(GGLfixed x, GGLfixed y, GGLfixed a, int shift) CONST;
inline GGLfixed gglMulAddx(GGLfixed x, GGLfixed y, GGLfixed a, int shift)
{
    GGLfixed result;
    asm("smull  %x[result], %w[x], %w[y]                     \n"
        "lsr    %x[result], %x[result], %x[shift]            \n"
        "add    %w[result], %w[result], %w[a]                \n"
        : [result]"=&r"(result)                               \
        : [x]"r"(x), [y]"r"(y), [a]"r"(a), [shift] "r"(shift) \
        :
        );
    return result;
}

inline GGLfixed gglMulSubx(GGLfixed x, GGLfixed y, GGLfixed a, int shift) CONST;
inline GGLfixed gglMulSubx(GGLfixed x, GGLfixed y, GGLfixed a, int shift)
{

    GGLfixed result;
    int rshift;

    asm("smull  %x[result], %w[x], %w[y]                     \n"
        "lsr    %x[result], %x[result], %x[shift]            \n"
        "sub    %w[result], %w[result], %w[a]                \n"
        : [result]"=&r"(result)                               \
        : [x]"r"(x), [y]"r"(y), [a]"r"(a), [shift] "r"(shift) \
        :
        );
    return result;
}
inline int64_t gglMulii(int32_t x, int32_t y) CONST;
inline int64_t gglMulii(int32_t x, int32_t y)
{
    int64_t res;
    asm("smull  %x0, %w1, %w2 \n"
        : "=r"(res)
        : "%r"(x), "r"(y)
        :
        );
    return res;
}

#else // ----------------------------------------------------------------------

inline GGLfixed gglMulx(GGLfixed a, GGLfixed b, int shift) CONST;
inline GGLfixed gglMulx(GGLfixed a, GGLfixed b, int shift) {
    return GGLfixed((int64_t(a)*b + (1<<(shift-1)))>>shift);
}
inline GGLfixed gglMulAddx(GGLfixed a, GGLfixed b, GGLfixed c, int shift) CONST;
inline GGLfixed gglMulAddx(GGLfixed a, GGLfixed b, GGLfixed c, int shift) {
    return GGLfixed((int64_t(a)*b)>>shift) + c;
}
inline GGLfixed gglMulSubx(GGLfixed a, GGLfixed b, GGLfixed c, int shift) CONST;
inline GGLfixed gglMulSubx(GGLfixed a, GGLfixed b, GGLfixed c, int shift) {
    return GGLfixed((int64_t(a)*b)>>shift) - c;
}
inline int64_t gglMulii(int32_t a, int32_t b) CONST;
inline int64_t gglMulii(int32_t a, int32_t b) {
    return int64_t(a)*b;
}

#endif

// ------------------------------------------------------------------------

inline GGLfixed gglMulx(GGLfixed a, GGLfixed b) CONST;
inline GGLfixed gglMulx(GGLfixed a, GGLfixed b) {
    return gglMulx(a, b, 16);
}
inline GGLfixed gglMulAddx(GGLfixed a, GGLfixed b, GGLfixed c) CONST;
inline GGLfixed gglMulAddx(GGLfixed a, GGLfixed b, GGLfixed c) {
    return gglMulAddx(a, b, c, 16);
}
inline GGLfixed gglMulSubx(GGLfixed a, GGLfixed b, GGLfixed c) CONST;
inline GGLfixed gglMulSubx(GGLfixed a, GGLfixed b, GGLfixed c) {
    return gglMulSubx(a, b, c, 16);
}

// ------------------------------------------------------------------------

inline int32_t gglClz(int32_t x) CONST;
inline int32_t gglClz(int32_t x)
{
#if (defined(__arm__) && !defined(__thumb__)) || defined(__mips__) || defined(__aarch64__)
    return __builtin_clz(x);
#else
    if (!x) return 32;
    int32_t exp = 31;
    if (x & 0xFFFF0000) { exp -=16; x >>= 16; }
    if (x & 0x0000ff00) { exp -= 8; x >>= 8; }
    if (x & 0x000000f0) { exp -= 4; x >>= 4; }
    if (x & 0x0000000c) { exp -= 2; x >>= 2; }
    if (x & 0x00000002) { exp -= 1; }
    return exp;
#endif
}

// ------------------------------------------------------------------------

int32_t gglDivQ(GGLfixed n, GGLfixed d, int32_t i) CONST;

inline int32_t gglDivQ16(GGLfixed n, GGLfixed d) CONST;
inline int32_t gglDivQ16(GGLfixed n, GGLfixed d) {
    return gglDivQ(n, d, 16);
}

inline int32_t gglDivx(GGLfixed n, GGLfixed d) CONST;
inline int32_t gglDivx(GGLfixed n, GGLfixed d) {
    return gglDivQ(n, d, 16);
}

// ------------------------------------------------------------------------

inline GGLfixed gglRecipFast(GGLfixed x) CONST;
inline GGLfixed gglRecipFast(GGLfixed x)
{
    // This is a really bad approximation of 1/x, but it's also
    // very fast. x must be strictly positive.
    // if x between [0.5, 1[ , then 1/x = 3-2*x
    // (we use 2.30 fixed-point)
    const int32_t lz = gglClz(x);
    return (0xC0000000 - (x << (lz - 1))) >> (30-lz);
}

// ------------------------------------------------------------------------

inline GGLfixed gglClampx(GGLfixed c) CONST;
inline GGLfixed gglClampx(GGLfixed c)
{
#if defined(__thumb__)
    // clamp without branches
    c &= ~(c>>31);  c = FIXED_ONE - c;
    c &= ~(c>>31);  c = FIXED_ONE - c;
#else
#if defined(__arm__)
    // I don't know why gcc thinks its smarter than me! The code below
    // clamps to zero in one instruction, but gcc won't generate it and
    // replace it by a cmp + movlt (it's quite amazing actually).
    asm("bic %0, %1, %1, asr #31\n" : "=r"(c) : "r"(c));
#elif defined(__aarch64__)
    asm("bic %w0, %w1, %w1, asr #31\n" : "=r"(c) : "r"(c));
#else
    c &= ~(c>>31);
#endif
    if (c>FIXED_ONE)
        c = FIXED_ONE;
#endif
    return c;
}

// ------------------------------------------------------------------------

#endif // ANDROID_GGL_FIXED_H