€•m&      Œsphinx.addnodes”Œdocument”“”)”}”(Œ	rawsource”Œ ”Œchildren”]”(Œtranslations”ŒLanguagesNode”“”)”}”(hhh]”(h Œpending_xref”“”)”}”(hhh]”Œdocutils.nodes”ŒText”“”ŒChinese (Simplified)”…””}”Œparent”hsbaŒ
attributes”}”(Œids”]”Œclasses”]”Œnames”]”Œdupnames”]”Œbackrefs”]”Œ	refdomain”Œstd”Œreftype”Œdoc”Œ	reftarget”Œ"/translations/zh_CN/fb/cmap_xfbdev”Œmodname”NŒ	classname”NŒrefexplicit”ˆuŒtagname”hhhubh)”}”(hhh]”hŒChinese (Traditional)”…””}”hh2sbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ"/translations/zh_TW/fb/cmap_xfbdev”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒItalian”…””}”hhFsbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ"/translations/it_IT/fb/cmap_xfbdev”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒJapanese”…””}”hhZsbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ"/translations/ja_JP/fb/cmap_xfbdev”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒKorean”…””}”hhnsbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ"/translations/ko_KR/fb/cmap_xfbdev”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒSpanish”…””}”hh‚sbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ"/translations/sp_SP/fb/cmap_xfbdev”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubeh}”(h]”h ]”h"]”h$]”h&]”Œcurrent_language”ŒEnglish”uh1h
hhŒ	_document”hŒsource”NŒline”NubhŒsection”“”)”}”(hhh]”(hŒtitle”“”)”}”(hŒUnderstanding fbdev's cmap”h]”hŒUnderstanding fbdevâ€™s cmap”…””}”(hh¨hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h¦hh£hžhhŸŒ</var/lib/git/docbuild/linux/Documentation/fb/cmap_xfbdev.rst”h KubhŒ	paragraph”“”)”}”(hŒCThese notes explain how X's dix layer uses fbdev's cmap structures.”h]”hŒGThese notes explain how Xâ€™s dix layer uses fbdevâ€™s cmap structures.”…””}”(hh¹hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Khh£hžhubhŒbullet_list”“”)”}”(hhh]”(hŒ	list_item”“”)”}”(hX/  example of relevant structures in fbdev as used for a 3-bit grayscale cmap::

 struct fb_var_screeninfo {
         .bits_per_pixel = 8,
         .grayscale      = 1,
         .red =          { 4, 3, 0 },
         .green =        { 0, 0, 0 },
         .blue =         { 0, 0, 0 },
 }
 struct fb_fix_screeninfo {
         .visual =       FB_VISUAL_STATIC_PSEUDOCOLOR,
 }
 for (i = 0; i < 8; i++)
     info->cmap.red[i] = (((2*i)+1)*(0xFFFF))/16;
 memcpy(info->cmap.green, info->cmap.red, sizeof(u16)*8);
 memcpy(info->cmap.blue, info->cmap.red, sizeof(u16)*8);
”h]”(h¸)”}”(hŒLexample of relevant structures in fbdev as used for a 3-bit grayscale cmap::”h]”hŒKexample of relevant structures in fbdev as used for a 3-bit grayscale cmap:”…””}”(hhÒhžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h KhhÎubhŒliteral_block”“”)”}”(hXÒ  struct fb_var_screeninfo {
        .bits_per_pixel = 8,
        .grayscale      = 1,
        .red =          { 4, 3, 0 },
        .green =        { 0, 0, 0 },
        .blue =         { 0, 0, 0 },
}
struct fb_fix_screeninfo {
        .visual =       FB_VISUAL_STATIC_PSEUDOCOLOR,
}
for (i = 0; i < 8; i++)
    info->cmap.red[i] = (((2*i)+1)*(0xFFFF))/16;
memcpy(info->cmap.green, info->cmap.red, sizeof(u16)*8);
memcpy(info->cmap.blue, info->cmap.red, sizeof(u16)*8);”h]”hXÒ  struct fb_var_screeninfo {
        .bits_per_pixel = 8,
        .grayscale      = 1,
        .red =          { 4, 3, 0 },
        .green =        { 0, 0, 0 },
        .blue =         { 0, 0, 0 },
}
struct fb_fix_screeninfo {
        .visual =       FB_VISUAL_STATIC_PSEUDOCOLOR,
}
for (i = 0; i < 8; i++)
    info->cmap.red[i] = (((2*i)+1)*(0xFFFF))/16;
memcpy(info->cmap.green, info->cmap.red, sizeof(u16)*8);
memcpy(info->cmap.blue, info->cmap.red, sizeof(u16)*8);”…””}”hhâsbah}”(h]”h ]”h"]”h$]”h&]”Œ	xml:space”Œpreserve”uh1hàhŸh¶h K	hhÎubeh}”(h]”h ]”h"]”h$]”h&]”uh1hÌhhÉhžhhŸh¶h NubhÍ)”}”(hX²  X11 apps do something like the following when trying to use grayscale::

 for (i=0; i < 8; i++) {
     char colorspec[64];
     memset(colorspec,0,64);
     sprintf(colorspec, "rgb:%x/%x/%x", i*36,i*36,i*36);
     if (!XParseColor(outputDisplay, testColormap, colorspec, &wantedColor))
             printf("Can't get color %s\n",colorspec);
     XAllocColor(outputDisplay, testColormap, &wantedColor);
     grays[i] = wantedColor;
 }
”h]”(h¸)”}”(hŒGX11 apps do something like the following when trying to use grayscale::”h]”hŒFX11 apps do something like the following when trying to use grayscale:”…””}”(hhühžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Khhøubhá)”}”(hX_  for (i=0; i < 8; i++) {
    char colorspec[64];
    memset(colorspec,0,64);
    sprintf(colorspec, "rgb:%x/%x/%x", i*36,i*36,i*36);
    if (!XParseColor(outputDisplay, testColormap, colorspec, &wantedColor))
            printf("Can't get color %s\n",colorspec);
    XAllocColor(outputDisplay, testColormap, &wantedColor);
    grays[i] = wantedColor;
}”h]”hX_  for (i=0; i < 8; i++) {
    char colorspec[64];
    memset(colorspec,0,64);
    sprintf(colorspec, "rgb:%x/%x/%x", i*36,i*36,i*36);
    if (!XParseColor(outputDisplay, testColormap, colorspec, &wantedColor))
            printf("Can't get color %s\n",colorspec);
    XAllocColor(outputDisplay, testColormap, &wantedColor);
    grays[i] = wantedColor;
}”…””}”hj
  sbah}”(h]”h ]”h"]”h$]”h&]”hðhñuh1hàhŸh¶h Khhøubeh}”(h]”h ]”h"]”h$]”h&]”uh1hÌhhÉhžhhŸh¶h Nubeh}”(h]”h ]”h"]”h$]”h&]”Œbullet”Œ-”uh1hÇhŸh¶h Khh£hžhubh¸)”}”(hŒJThere's also named equivalents like gray1..x provided you have an rgb.txt.”h]”hŒLThereâ€™s also named equivalents like gray1..x provided you have an rgb.txt.”…””}”(hj&  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h K$hh£hžhubh¸)”}”(hŒSomewhere in X's callchain, this results in a call to X code that handles the
colormap. For example, Xfbdev hits the following:”h]”hŒSomewhere in Xâ€™s callchain, this results in a call to X code that handles the
colormap. For example, Xfbdev hits the following:”…””}”(hj4  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h K&hh£hžhubh¸)”}”(hŒ+xc-011010/programs/Xserver/dix/colormap.c::”h]”hŒ*xc-011010/programs/Xserver/dix/colormap.c:”…””}”(hjB  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h K)hh£hžhubhá)”}”(hX  FindBestPixel(pentFirst, size, prgb, channel)

dr = (long) pent->co.local.red - prgb->red;
dg = (long) pent->co.local.green - prgb->green;
db = (long) pent->co.local.blue - prgb->blue;
sq = dr * dr;
UnsignedToBigNum (sq, &sum);
BigNumAdd (&sum, &temp, &sum);”h]”hX  FindBestPixel(pentFirst, size, prgb, channel)

dr = (long) pent->co.local.red - prgb->red;
dg = (long) pent->co.local.green - prgb->green;
db = (long) pent->co.local.blue - prgb->blue;
sq = dr * dr;
UnsignedToBigNum (sq, &sum);
BigNumAdd (&sum, &temp, &sum);”…””}”hjP  sbah}”(h]”h ]”h"]”h$]”h&]”hðhñuh1hàhŸh¶h K+hh£hžhubh¸)”}”(hX_  co.local.red are entries that were brought in through FBIOGETCMAP which come
directly from the info->cmap.red that was listed above. The prgb is the rgb
that the app wants to match to. The above code is doing what looks like a least
squares matching function. That's why the cmap entries can't be set to the left
hand side boundaries of a color range.”h]”hXc  co.local.red are entries that were brought in through FBIOGETCMAP which come
directly from the info->cmap.red that was listed above. The prgb is the rgb
that the app wants to match to. The above code is doing what looks like a least
squares matching function. Thatâ€™s why the cmap entries canâ€™t be set to the left
hand side boundaries of a color range.”…””}”(hj^  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h K4hh£hžhubeh}”(h]”Œunderstanding-fbdev-s-cmap”ah ]”h"]”Œunderstanding fbdev's cmap”ah$]”h&]”uh1h¡hhhžhhŸh¶h Kubeh}”(h]”h ]”h"]”h$]”h&]”Œsource”h¶uh1hŒcurrent_source”NŒcurrent_line”NŒsettings”Œdocutils.frontend”ŒValues”“”)”}”(h¦NŒ	generator”NŒ	datestamp”NŒsource_link”NŒ
source_url”NŒtoc_backlinks”Œentry”Œfootnote_backlinks”KŒsectnum_xform”KŒstrip_comments”NŒstrip_elements_with_classes”NŒstrip_classes”NŒreport_level”KŒ
halt_level”KŒexit_status_level”KŒdebug”NŒwarning_stream”NŒ	traceback”ˆŒinput_encoding”Œ	utf-8-sig”Œinput_encoding_error_handler”Œstrict”Œoutput_encoding”Œutf-8”Œoutput_encoding_error_handler”j—  Œerror_encoding”Œutf-8”Œerror_encoding_error_handler”Œbackslashreplace”Œlanguage_code”Œen”Œrecord_dependencies”NŒconfig”NŒ	id_prefix”hŒauto_id_prefix”Œid”Œdump_settings”NŒdump_internals”NŒdump_transforms”NŒdump_pseudo_xml”NŒexpose_internals”NŒstrict_visitor”NŒ_disable_config”NŒ_source”h¶Œ_destination”NŒ_config_files”]”Œ7/var/lib/git/docbuild/linux/Documentation/docutils.conf”aŒfile_insertion_enabled”ˆŒraw_enabled”KŒline_length_limit”M'Œpep_references”NŒpep_base_url”Œhttps://peps.python.org/”Œpep_file_url_template”Œpep-%04d”Œrfc_references”NŒrfc_base_url”Œ&https://datatracker.ietf.org/doc/html/”Œ	tab_width”KŒtrim_footnote_reference_space”‰Œsyntax_highlight”Œlong”Œsmart_quotes”ˆŒsmartquotes_locales”]”Œcharacter_level_inline_markup”‰Œdoctitle_xform”‰Œdocinfo_xform”KŒsectsubtitle_xform”‰Œimage_loading”Œlink”Œembed_stylesheet”‰Œcloak_email_addresses”ˆŒsection_self_link”‰Œenv”NubŒreporter”NŒindirect_targets”]”Œsubstitution_defs”}”Œsubstitution_names”}”Œrefnames”}”Œrefids”}”Œnameids”}”jq  jn  sŒ	nametypes”}”jq  ‰sh}”jn  h£sŒfootnote_refs”}”Œcitation_refs”}”Œautofootnotes”]”Œautofootnote_refs”]”Œsymbol_footnotes”]”Œsymbol_footnote_refs”]”Œ	footnotes”]”Œ	citations”]”Œautofootnote_start”KŒsymbol_footnote_start”K Œ
id_counter”Œcollections”ŒCounter”“”}”…”R”Œparse_messages”]”Œtransform_messages”]”Œtransformer”NŒinclude_log”]”Œ
decoration”Nhžhub.