On Wed, 03 Oct 2018 10:11:46 +0100 Chris Wilson <ch...@chris-wilson.co.uk> wrote:
> Quoting Maarten Lankhorst (2018-08-01 13:41:33) > > diff --git a/pixman/pixman.h b/pixman/pixman.h > > index 509ba5e534a8..c9bf4faa80d4 100644 > > --- a/pixman/pixman.h > > +++ b/pixman/pixman.h > > @@ -647,19 +647,24 @@ struct pixman_indexed > > * sample implementation allows only packed RGB and GBR > > * representations for data to simplify software rendering, > > */ > > -#define PIXMAN_FORMAT(bpp,type,a,r,g,b) (((bpp) << 24) | \ > > +#define PIXMAN_FORMAT_PACKC(val) ((val) <= 10 ? (val) : \ > > + (val) == 32 ? 11 : 0) > > +#define PIXMAN_FORMAT_UNPACKC(val) ((val) <= 10 ? (val) : \ > > + (val) == 11 ? 32 : 0) > > We have 4bits, why not reserve 0xf for float32? Certainly you > want space for > > #define PIXMAN_FORMAT_PACKED_FLOAT16 0xb > #define PIXMAN_FORMAT_PACKED_FLOAT32 0xc > #define PIXMAN_FORMAT_PACKED_FLOAT64 0xd > > I just wonder if we may have 12bpc one day as well, so leaving 0xc clear > has some some appeal. We could probably also try to do something like this: /* * While the protocol is generous in format support, the * sample implementation allows only packed RGB and GBR * representations for data to simplify software rendering, * * Bit 23 selects the granularity of channel color depth * 0: 1-bit granularity (allows up to 15 bits per channel) * 1: 1-byte granularity (allows up to 120 bits per channel) */ #define PIXMAN_FORMAT(bpp,type,a,r,g,b) \ (((bpp) << 24) | \ ((type) << 16) | \ (((a) < 16) ? ((a) << 12) : (((a / 8) << 12) | (1 << 23))) | \ (((r) < 16) ? ((r) << 8) : (((r / 8) << 8) | (1 << 23))) | \ (((g) < 16) ? ((g) << 4) : (((g / 8) << 4) | (1 << 23))) | \ (((b) < 16) ? ((b)) : (((b / 8)) | (1 << 23)))) /* 0 for 1-bit granularity and 3 for 1-byte granularity */ #define PIXMAN_FORMAT_CHANDEPTH_SHIFT(f) \ ((((f) >> 23) & 1) | ((((f) >> 23) & 1) << 1)) #define PIXMAN_FORMAT_A(f) \ ((((f) >> 12) & 0x0f) << PIXMAN_FORMAT_CHANDEPTH_SHIFT(f)) #define PIXMAN_FORMAT_R(f) \ ((((f) >> 8) & 0x0f) << PIXMAN_FORMAT_CHANDEPTH_SHIFT(f)) #define PIXMAN_FORMAT_G(f) \ ((((f) >> 4) & 0x0f) << PIXMAN_FORMAT_CHANDEPTH_SHIFT(f)) #define PIXMAN_FORMAT_B(f) \ ((((f) ) & 0x0f) << PIXMAN_FORMAT_CHANDEPTH_SHIFT(f)) #define PIXMAN_FORMAT_BPP(f) (((uint32_t)(f)) >> 24) #define PIXMAN_FORMAT_TYPE(f) (((f) >> 16) & 0x7f) #define PIXMAN_FORMAT_RGB(f) (((f) ) & 0xfff) #define PIXMAN_FORMAT_VIS(f) (((f) ) & 0xffff) #define PIXMAN_FORMAT_DEPTH(f) (PIXMAN_FORMAT_A(f) + \ PIXMAN_FORMAT_R(f) + \ PIXMAN_FORMAT_G(f) + \ PIXMAN_FORMAT_B(f)) Right now the format type occupies 8 bits. The highest bit could be repurposed as a flag for storing channel depth as bytes instead of bits. This way 16-bit and 64-bit per color component will be also supported. The limitation of this approach is that the depth of every color component has to be a multiple of 8 bits if any of them is 16 bits or larger. I don't feel very comfortable about the fact that some applications are using the PIXMAN_FORMAT_A/R/G/B macros and this code gets compiled as part of these application binaries. Are there any other interesting >32bpp formats that we may need to support in the future? -- Best regards, Siarhei Siamashka _______________________________________________ Pixman mailing list Pixman@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/pixman