From 3f31b9852c313b6b9a670e9c202a7fb339e5d448 Mon Sep 17 00:00:00 2001
From: "H. Peter Anvin" <hpa@zytor.com>
Date: Mon, 28 Aug 2006 01:50:09 -0700
Subject: [PATCH] Work on getting libpng to actually do something useful...

---
 com32/lib/MCONFIG               | 12 +++++++++---
 com32/lib/Makefile              |  6 ++++--
 com32/lib/math/pow.S            | 25 +++++++++++++++++++++++++
 com32/lib/sys/vesa/background.c | 18 +++++-------------
 4 files changed, 43 insertions(+), 18 deletions(-)
 create mode 100644 com32/lib/math/pow.S

diff --git a/com32/lib/MCONFIG b/com32/lib/MCONFIG
index 35d34d7c..1263b516 100644
--- a/com32/lib/MCONFIG
+++ b/com32/lib/MCONFIG
@@ -12,12 +12,18 @@ OBJCOPY	= objcopy
 
 # zlib and libpng configuration flags
 LIBFLAGS = -DDYNAMIC_CRC_TABLE -DPNG_NO_CONSOLE_IO \
-	   -DPNG_NO_MNG_FEATURES -DPNG_NO_FLOATING_POINT_SUPPORTED \
-	   -DPNG_NO_WRITE_FLUSH -DPNG_NO_WRITE_tIME -DPNG_NO_READ_tIME
+	   -FPNG_NO_WRITE_SUPPORTED \
+	   -DPNG_NO_MNG_FEATURES \
+	   -DPNG_NO_READ_tIME -DPNG_NO_WRITE_tIME
+
+# We need some features in libpng which apparently aren't available in the
+# fixed-point versions.  It's OK, because we have to have a non-graphical
+# fallback anyway, just use that on old machines...
+# LIBFLAGS += -DPNG_NO_FLOATING_POINT_SUPPORTED
 
 REQFLAGS  = -g -m32 -mregparm=3 -DREGPARM=3 -D__COM32__ -I. -I./sys -I../include
 OPTFLAGS  = -Os -march=i386 -falign-functions=0 -falign-jumps=0 \
-	    -falign-labels=0
+	    -falign-labels=0 -ffast-math
 WARNFLAGS = -W -Wall -Wpointer-arith -Wwrite-strings -Wstrict-prototypes -Winline
 
 CFLAGS  = -Wp,-MT,$@,-MD,$(dir $@).$(notdir $@).d $(OPTFLAGS) \
diff --git a/com32/lib/Makefile b/com32/lib/Makefile
index cfbeeb22..a3aaa51d 100644
--- a/com32/lib/Makefile
+++ b/com32/lib/Makefile
@@ -44,11 +44,13 @@ LIBOBJS = \
 	zlib/uncompr.o zlib/deflate.o zlib/trees.o zlib/zutil.o 	\
 	zlib/inflate.o zlib/infback.o zlib/inftrees.o zlib/inffast.o	\
 	\
-	libpng/png.o libpng/pngset.o libpng/pngrutil.o			\
+	libpng/png.o libpng/pngset.o libpng/pngget.o libpng/pngrutil.o  \
 	libpng/pngtrans.o libpng/pngwutil.o libpng/pngread.o		\
 	libpng/pngrio.o libpng/pngwio.o libpng/pngwrite.o		\
 	libpng/pngrtran.o libpng/pngwtran.o libpng/pngmem.o		\
-	libpng/pngerror.o libpng/pngpread.o
+	libpng/pngerror.o libpng/pngpread.o				\
+	\
+	math/pow.o
 
 BINDIR   = /usr/bin
 LIBDIR   = /usr/lib
diff --git a/com32/lib/math/pow.S b/com32/lib/math/pow.S
new file mode 100644
index 00000000..5a124aba
--- /dev/null
+++ b/com32/lib/math/pow.S
@@ -0,0 +1,25 @@
+#
+# pow.S
+#
+# double pow(double base, double exponent)
+#
+
+	.text
+	.globl	pow
+	.type	pow,@function
+pow:
+	fldl	12(%esp)
+	fldl	4(%esp)
+	fyl2x
+	fld	%st(0)
+	frndint
+	fsubr	%st,%st(1)
+	fxch	%st(1)
+	f2xm1
+	fld1
+	faddp	%st,%st(1)
+	fscale
+	fstp	%st(1)
+	ret
+
+	.size	pow,.-pow
diff --git a/com32/lib/sys/vesa/background.c b/com32/lib/sys/vesa/background.c
index 7de2d5a4..5a34ef82 100644
--- a/com32/lib/sys/vesa/background.c
+++ b/com32/lib/sys/vesa/background.c
@@ -55,8 +55,6 @@ int vesacon_load_background(const char *filename)
   png_infop end_ptr = NULL;
   png_color_16p image_background;
   static const png_color_16 my_background = {0,0,0,0,0};
-  double gamma;
-  const double screen_gamma = 2.2;
   png_bytep row_pointers[VIDEO_Y_SIZE];
   int passes;
   int i;
@@ -123,6 +121,11 @@ int vesacon_load_background(const char *filename)
 
   png_set_bgr(png_ptr);
 
+  if (info_ptr->bit_depth == 16)
+    png_set_strip_16(png_ptr);
+  else if (info_ptr->bit_depth < 8)
+    png_set_packing(png_ptr);
+
   if (png_get_bKGD(png_ptr, info_ptr, &image_background))
     png_set_background(png_ptr, image_background,
 		       PNG_BACKGROUND_GAMMA_FILE, 1, 1.0);
@@ -130,17 +133,6 @@ int vesacon_load_background(const char *filename)
     png_set_background(png_ptr, &my_background,
 		       PNG_BACKGROUND_GAMMA_SCREEN, 0, 1.0);
     
-
-  if (info_ptr->bit_depth == 16)
-    png_set_strip_16(png_ptr);
-  else if (info_ptr->bit_depth < 8)
-    png_set_packing(png_ptr);
-
-  if (png_get_gAMA(png_ptr, info_ptr, &gamma))
-    png_set_gamma(png_ptr, screen_gamma, gamma);
-  else
-    png_set_gamma(png_ptr, screen_gamma, 0.45455);
-
   /* Whew!  Now we should get the stuff we want... */
   for (i = 0; i < info_ptr->height; i++)
     row_pointers[i] = (png_bytep *)__vesacon_background[i];
-- 
2.11.4.GIT