rockbox/apps/codecs/libwma/wmafixed.h

/* 	fixed precision code.  We use a combination of Sign 15.16 and Sign.31
	precision here.

	The WMA decoder does not always follow this convention, and occasionally
	renormalizes values to other formats in order to maximize precision.
	However, only the two precisions above are provided in this file.

*/


#define PRECISION       16
#define PRECISION64     16


#define fixtof64(x)       (float)((float)(x) / (float)(1 << PRECISION64))        //does not work on int64_t!
#define ftofix32(x)       ((fixed32)((x) * (float)(1 << PRECISION) + ((x) < 0 ? -0.5 : 0.5)))
#define itofix64(x)       (IntTo64(x))
#define itofix32(x)       ((x) << PRECISION)
#define fixtoi32(x)       ((x) >> PRECISION)
#define fixtoi64(x)       (IntFrom64(x))


/*fixed functions*/

fixed64 IntTo64(int x);
int IntFrom64(fixed64 x);
fixed32 Fixed32From64(fixed64 x);
fixed64 Fixed32To64(fixed32 x);
fixed64 fixmul64byfixed(fixed64 x, fixed32 y);
fixed32 fixdiv32(fixed32 x, fixed32 y);
fixed64 fixdiv64(fixed64 x, fixed64 y);
fixed32 fixsqrt32(fixed32 x);
fixed32 fixsin32(fixed32 x);
fixed32 fixcos32(fixed32 x);
long fsincos(unsigned long phase, fixed32 *cos);





#ifdef CPU_ARM

/*
	Fixed precision multiply code ASM.

*/

/*Sign-15.16 format */

#define fixmul32(x, y)  \
    ({ int32_t __hi;  \
       uint32_t __lo;  \
       int32_t __result;  \
       asm ("smull   %0, %1, %3, %4\n\t"  \
            "movs    %0, %0, lsr %5\n\t"  \
            "adc    %2, %0, %1, lsl %6"  \
            : "=&r" (__lo), "=&r" (__hi), "=r" (__result)  \
            : "%r" (x), "r" (y),  \
              "M" (PRECISION), "M" (32 - PRECISION)  \
            : "cc");  \
       __result;  \
    })


 #define fixmul32b(x, y)  \
    ({ int32_t __hi;  \
       uint32_t __lo;  \
       int32_t __result;  \
       asm ("smull   %0, %1, %3, %4\n\t"  \
            "movs    %2, %1, lsl #1"  \
            : "=&r" (__lo), "=&r" (__hi), "=r" (__result)  \
            : "%r" (x), "r" (y)  \
            : "cc");  \
       __result;  \
    })

#elif defined(CPU_COLDFIRE)
static inline int32_t fixmul32(int32_t x, int32_t y)
{
#if PRECISION != 16
#warning Coldfire fixmul32() only works for PRECISION == 16
#endif
    int32_t t1;
    asm (
        "mac.l   %[x], %[y], %%acc0  \n" /* multiply */
        "mulu.l  %[y], %[x]      \n"     /* get lower half, avoid emac stall */
        "movclr.l %%acc0, %[t1]  \n"     /* get higher half */
        "lsr.l   #1, %[t1]       \n"
        "move.w  %[t1], %[x]     \n"
        "swap    %[x]            \n"
        : /* outputs */
        [t1]"=&d"(t1),
        [x] "+d" (x)
        : /* inputs */
        [y] "d"  (y)
    );
    return x;
}

fixed32 fixmul32b(fixed32 x, fixed32 y);
#else

fixed32 fixmul32(fixed32 x, fixed32 y);
fixed32 fixmul32b(fixed32 x, fixed32 y);
#endif


#ifdef CPU_ARM
static inline
void CMUL(fixed32 *x, fixed32 *y,
          fixed32  a, fixed32  b,
          fixed32  t, fixed32  v)
{
    /* This version loses one bit of precision. Could be solved at the cost
     * of 2 extra cycles if it becomes an issue. */
    int x1, y1, l;
    asm(
        "smull    %[l], %[y1], %[b], %[t] \n"
        "smlal    %[l], %[y1], %[a], %[v] \n"
        "rsb      %[b], %[b], #0          \n"
        "smull    %[l], %[x1], %[a], %[t] \n"
        "smlal    %[l], %[x1], %[b], %[v] \n"
        : [l] "=&r" (l), [x1]"=&r" (x1), [y1]"=&r" (y1), [b] "+r" (b)
        : [a] "r" (a),   [t] "r" (t),    [v] "r" (v)
        : "cc"
    );
    *x = x1 << 1;
    *y = y1 << 1;
}
#elif defined CPU_COLDFIRE
static inline
void CMUL(fixed32 *x, fixed32 *y,
          fixed32  a, fixed32  b,
          fixed32  t, fixed32  v)
{
  asm volatile ("mac.l %[a], %[t], %%acc0;"
                "msac.l %[b], %[v], %%acc0;"
                "mac.l %[b], %[t], %%acc1;"
                "mac.l %[a], %[v], %%acc1;"
                "movclr.l %%acc0, %[a];"
                "move.l %[a], (%[x]);"
                "movclr.l %%acc1, %[a];"
                "move.l %[a], (%[y]);"
                : [a] "+&r" (a)
                : [x] "a" (x), [y] "a" (y),
                  [b] "r" (b), [t] "r" (t), [v] "r" (v)
                : "cc", "memory");
}
#else
// PJJ : reinstate macro
static inline
void CMUL(fixed32 *pre,
          fixed32 *pim,
          fixed32 are,
          fixed32 aim,
          fixed32 bre,
          fixed32 bim)
{
    //int64_t x,y;
    fixed32 _aref = are;
    fixed32 _aimf = aim;
    fixed32 _bref = bre;
    fixed32 _bimf = bim;
    fixed32 _r1 = fixmul32b(_bref, _aref);
    fixed32 _r2 = fixmul32b(_bimf, _aimf);
    fixed32 _r3 = fixmul32b(_bref, _aimf);
    fixed32 _r4 = fixmul32b(_bimf, _aref);
    *pre = _r1 - _r2;
    *pim = _r3 + _r4;

}
#endif