iomfsetgamma.c

   1 #include <mach/mach.h>
   2
   3 #include <stdio.h>
   4 #include <stdlib.h>
   5
   6 #include <dlfcn.h>
   7
   8 #include <IOKit/IOKitLib.h>
   9
  10 #if 0
  11 set -e
  12
  13 sdk=/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS4.3.sdk
  14
  15 /Developer/Platforms/iPhoneOS.platform/Developer/usr/bin/g++ \
  16     -Wall -fmessage-length=0 \
  17     -arch armv6 -miphoneos-version-min=2.0 \
  18     -isysroot "${sdk}" -I. -F"${sdk}"/System/Library/PrivateFrameworks \
  19     -framework IOKit -framework IOMobileFramebuffer \
  20     -o iomfsetgamma iomfsetgamma.c
  21
  22 ldid iomfsetgamma
  23
  24 exit 0
  25 #endif
  26
  27 typedef void *IOMobileFramebufferRef;
  28
  29 kern_return_t IOMobileFramebufferOpen(io_service_t, mach_port_t, void *, IOMobileFramebufferRef *);
  30 kern_return_t IOMobileFramebufferSetGammaTable(IOMobileFramebufferRef, void *);
  31 kern_return_t (*$IOMobileFramebufferGetGammaTable)(IOMobileFramebufferRef, void *);
  32
  33 #define _assert(test) \
  34     if (!(test)) { \
  35         fprintf(stderr, "_assert(%s)\n", #test); \
  36         exit(-1); \
  37     }
  38
  39 int main(int argc, char *argv[]) {
  40     if (argc != 4) {
  41         fprintf(stderr, "usage: iomfsetgamma <red> <green> <blue>\n");
  42         fprintf(stderr, "  example: 1.00 0.78 0.64\n");
  43         return 1;
  44     }
  45
  46     unsigned rs = strtod(argv[1], NULL) * 0x100;
  47     _assert(rs <= 0x100);
  48
  49     unsigned gs = strtod(argv[2], NULL) * 0x100;
  50     _assert(gs <= 0x100);
  51
  52     unsigned bs = strtod(argv[3], NULL) * 0x100;
  53     _assert(bs <= 0x100);
  54
  55     kern_return_t error;
  56     mach_port_t self = mach_task_self();
  57
  58     io_service_t service = 0;
  59
  60     if (service == 0)
  61         service = IOServiceGetMatchingService(kIOMasterPortDefault, IOServiceMatching("AppleCLCD"));
  62     if (service == 0)
  63         service = IOServiceGetMatchingService(kIOMasterPortDefault, IOServiceMatching("AppleH1CLCD"));
  64     if (service == 0)
  65         service = IOServiceGetMatchingService(kIOMasterPortDefault, IOServiceMatching("AppleM2CLCD"));
  66
  67     _assert(service != 0);
  68
  69     IOMobileFramebufferRef fb;
  70     error = IOMobileFramebufferOpen(service, self, 0, &fb);
  71     _assert(error == 0);
  72
  73     uint32_t data[0xc00 / sizeof(uint32_t)];
  74     memset(data, 0, sizeof(data));
  75
  76     FILE *file = fopen("/tmp/.iomfgamma.dat", "r");
  77     if (file == NULL) {
  78         file = fopen("/tmp/.iomfgamma.dat", "wb");
  79
  80         $IOMobileFramebufferGetGammaTable = dlsym(RTLD_DEFAULT, "IOMobileFramebufferGetGammaTable");
  81
  82         _assert($IOMobileFramebufferGetGammaTable != NULL);
  83         error = $IOMobileFramebufferGetGammaTable(fb, data);
  84         _assert(error == 0);
  85
  86         fwrite(data, 1, sizeof(data), file);
  87         fclose(file);
  88
  89         file = fopen("/tmp/.iomfgamma.dat", "r");
  90     }
  91
  92     fread(data, 1, sizeof(data), file);
  93     fclose(file);
  94
  95     size_t i;
  96     for (i = 0; i != 256; ++i) {
  97         int j = 255 - i;
  98
  99         int r = j * rs >> 8;
 100         int g = j * gs >> 8;
 101         int b = j * bs >> 8;
 102
 103         data[j + 0x000] = data[r + 0x000];
 104         data[j + 0x100] = data[g + 0x100];
 105         data[j + 0x200] = data[b + 0x200];
 106     }
 107
 108     error = IOMobileFramebufferSetGammaTable(fb, data);
 109     _assert(error == 0);
 110
 111     return 0;
 112 }