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author | Alex Deucher <alexander.deucher@amd.com> | 2013-03-22 14:35:50 (GMT) |
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committer | Alex Deucher <alexander.deucher@amd.com> | 2013-06-27 23:16:37 (GMT) |
commit | 210a0b9e212370ed8c2784c2115e7ff4bb1259bd (patch) | |
tree | 35efeaaa2b97e7f4e0a9fe3475967bd859cf55d6 /include/drm/drm_fixed.h | |
parent | 9ed36f750534e2c6533fcbf32df89cf20cf87e91 (diff) | |
download | linux-fsl-qoriq-210a0b9e212370ed8c2784c2115e7ff4bb1259bd.tar.xz |
drm: add some additional fixed point helpers (v3)
Required for certain driver calculations. Code
was written by Christian König and ported to the
drm by me.
v2: fix 64 bit divides
v3: fix 64 bit for real (math64.h)
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Diffstat (limited to 'include/drm/drm_fixed.h')
-rw-r--r-- | include/drm/drm_fixed.h | 94 |
1 files changed, 94 insertions, 0 deletions
diff --git a/include/drm/drm_fixed.h b/include/drm/drm_fixed.h index 0ead502..f5e1168 100644 --- a/include/drm/drm_fixed.h +++ b/include/drm/drm_fixed.h @@ -20,10 +20,13 @@ * OTHER DEALINGS IN THE SOFTWARE. * * Authors: Dave Airlie + * Christian König */ #ifndef DRM_FIXED_H #define DRM_FIXED_H +#include <linux/math64.h> + typedef union dfixed { u32 full; } fixed20_12; @@ -65,4 +68,95 @@ static inline u32 dfixed_div(fixed20_12 A, fixed20_12 B) tmp /= 2; return lower_32_bits(tmp); } + +#define DRM_FIXED_POINT 32 +#define DRM_FIXED_ONE (1ULL << DRM_FIXED_POINT) +#define DRM_FIXED_DECIMAL_MASK (DRM_FIXED_ONE - 1) +#define DRM_FIXED_DIGITS_MASK (~DRM_FIXED_DECIMAL_MASK) + +static inline s64 drm_int2fixp(int a) +{ + return ((s64)a) << DRM_FIXED_POINT; +} + +static inline int drm_fixp2int(int64_t a) +{ + return ((s64)a) >> DRM_FIXED_POINT; +} + +static inline s64 drm_fixp_msbset(int64_t a) +{ + unsigned shift, sign = (a >> 63) & 1; + + for (shift = 62; shift > 0; --shift) + if ((a >> shift) != sign) + return shift; + + return 0; +} + +static inline s64 drm_fixp_mul(s64 a, s64 b) +{ + unsigned shift = drm_fixp_msbset(a) + drm_fixp_msbset(b); + s64 result; + + if (shift > 63) { + shift = shift - 63; + a >>= shift >> 1; + b >>= shift >> 1; + } else + shift = 0; + + result = a * b; + + if (shift > DRM_FIXED_POINT) + return result << (shift - DRM_FIXED_POINT); + + if (shift < DRM_FIXED_POINT) + return result >> (DRM_FIXED_POINT - shift); + + return result; +} + +static inline s64 drm_fixp_div(s64 a, s64 b) +{ + unsigned shift = 63 - drm_fixp_msbset(a); + s64 result; + + a <<= shift; + + if (shift < DRM_FIXED_POINT) + b >>= (DRM_FIXED_POINT - shift); + + result = div64_s64(a, b); + + if (shift > DRM_FIXED_POINT) + return result >> (shift - DRM_FIXED_POINT); + + return result; +} + +static inline s64 drm_fixp_exp(s64 x) +{ + s64 tolerance = div64_s64(DRM_FIXED_ONE, 1000000); + s64 sum = DRM_FIXED_ONE, term, y = x; + u64 count = 1; + + if (x < 0) + y = -1 * x; + + term = y; + + while (term >= tolerance) { + sum = sum + term; + count = count + 1; + term = drm_fixp_mul(term, div64_s64(y, count)); + } + + if (x < 0) + sum = drm_fixp_div(1, sum); + + return sum; +} + #endif |