/* pnggccrd.c - mixed C/assembler version of utilities to read a PNG file * * For Intel x86 CPU (Pentium-MMX or later) and GNU C compiler. * *     See http://www.intel.com/drg/pentiumII/appnotes/916/916.htm *     and http://www.intel.com/drg/pentiumII/appnotes/923/923.htm *     for Intel's performance analysis of the MMX vs. non-MMX code. * * libpng version 1.2.8 - December 3, 2004 * For conditions of distribution and use, see copyright notice in png.h * Copyright (c) 1998-2004 Glenn Randers-Pehrson * Copyright (c) 1998, Intel Corporation * * Based on MSVC code contributed by Nirav Chhatrapati, Intel Corp., 1998. * Interface to libpng contributed by Gilles Vollant, 1999. * GNU C port by Greg Roelofs, 1999-2001. * * Lines 2350-4300 converted in place with intel2gas 1.3.1: * *   intel2gas -mdI pnggccrd.c.partially-msvc -o pnggccrd.c * * and then cleaned up by hand.  See http://hermes.terminal.at/intel2gas/ . * * NOTE:  A sufficiently recent version of GNU as (or as.exe under DOS/Windows) *        is required to assemble the newer MMX instructions such as movq. *        For djgpp, see * *           ftp://ftp.simtel.net/pub/simtelnet/gnu/djgpp/v2gnu/bnu281b.zip * *        (or a later version in the same directory).  For Linux, check your *        distribution's web site(s) or try these links: * *           http://rufus.w3.org/linux/RPM/binutils.html *           http://www.debian.org/Packages/stable/devel/binutils.html *           ftp://ftp.slackware.com/pub/linux/slackware/slackware/slakware/d1/ *             binutils.tgz * *        For other platforms, see the main GNU site: * *           ftp://ftp.gnu.org/pub/gnu/binutils/ * *        Version 2.5.2l.15 is definitely too old... *//* * TEMPORARY PORTING NOTES AND CHANGELOG (mostly by Greg Roelofs) * ===================================== * * 19991006: *  - fixed sign error in post-MMX cleanup code (16- & 32-bit cases) * * 19991007: *  - additional optimizations (possible or definite): *     x [DONE] write MMX code for 64-bit case (pixel_bytes == 8) [not tested] *     - write MMX code for 48-bit case (pixel_bytes == 6) *     - figure out what's up with 24-bit case (pixel_bytes == 3): *        why subtract 8 from width_mmx in the pass 4/5 case? *        (only width_mmx case) (near line 1606) *     x [DONE] replace pixel_bytes within each block with the true *        constant value (or are compilers smart enough to do that?) *     - rewrite all MMX interlacing code so it's aligned with *        the *beginning* of the row buffer, not the end.  This *        would not only allow one to eliminate half of the memory *        writes for odd passes (that is, pass == odd), it may also *        eliminate some unaligned-data-access exceptions (assuming *        there's a penalty for not aligning 64-bit accesses on *        64-bit boundaries).  The only catch is that the "leftover" *        pixel(s) at the end of the row would have to be saved, *        but there are enough unused MMX registers in every case, *        so this is not a problem.  A further benefit is that the *        post-MMX cleanup code (C code) in at least some of the *        cases could be done within the assembler block. *  x [DONE] the "v3 v2 v1 v0 v7 v6 v5 v4" comments are confusing, *     inconsistent, and don't match the MMX Programmer's Reference *     Manual conventions anyway.  They should be changed to *     "b7 b6 b5 b4 b3 b2 b1 b0," where b0 indicates the byte that *     was lowest in memory (e.g., corresponding to a left pixel) *     and b7 is the byte that was highest (e.g., a right pixel). * * 19991016: *  - Brennan's Guide notwithstanding, gcc under Linux does *not* *     want globals prefixed by underscores when referencing them-- *     i.e., if the variable is const4, then refer to it as const4, *     not _const4.  This seems to be a djgpp-specific requirement. *     Also, such variables apparently *must* be declared outside *     of functions; neither static nor automatic variables work if *     defined within the scope of a single function, but both *     static and truly global (multi-module) variables work fine. * * 19991023: *  - fixed png_combine_row() non-MMX replication bug (odd passes only?) *  - switched from string-concatenation-with-macros to cleaner method of *     renaming global variables for djgpp--i.e., always use prefixes in *     inlined assembler code (== strings) and conditionally rename the *     variables, not the other way around.  Hence _const4, _mask8_0, etc. * * 19991024: *  - fixed mmxsupport()/png_do_read_interlace() first-row bug *     This one was severely weird:  even though mmxsupport() doesn't touch *     ebx (where "row" pointer was stored), it nevertheless managed to zero *     the register (even in static/non-fPIC code--see below), which in turn *     caused png_do_read_interlace() to return prematurely on the first row of *     interlaced images (i.e., without expanding the interlaced pixels). *     Inspection of the generated assembly code didn't turn up any clues, *     although it did point at a minor optimization (i.e., get rid of *     mmx_supported_local variable and just use eax).  Possibly the CPUID *     instruction is more destructive than it looks?  (Not yet checked.) *  - "info gcc" was next to useless, so compared fPIC and non-fPIC assembly *     listings...  Apparently register spillage has to do with ebx, since *     it's used to index the global offset table.  Commenting it out of the *     input-reg lists in png_combine_row() eliminated compiler barfage, so *     ifdef'd with __PIC__ macro:  if defined, use a global for unmask * * 19991107: *  - verified CPUID clobberage:  12-char string constant ("GenuineIntel", *     "AuthenticAMD", etc.) placed in ebx:ecx:edx.  Still need to polish. * * 19991120: *  - made "diff" variable (now "_dif") global to simplify conversion of *     filtering routines (running out of regs, sigh).  "diff" is still used *     in interlacing routines, however. *  - fixed up both versions of mmxsupport() (ORIG_THAT_USED_TO_CLOBBER_EBX *     macro determines which is used); original not yet tested. * * 20000213: *  - when compiling with gcc, be sure to use  -fomit-frame-pointer * * 20000319: *  - fixed a register-name typo in png_do_read_interlace(), default (MMX) case, *     pass == 4 or 5, that caused visible corruption of interlaced images * * 20000623: *  - Various problems were reported with gcc 2.95.2 in the Cygwin environment, *     many of the form "forbidden register 0 (ax) was spilled for class AREG." *     This is explained at http://gcc.gnu.org/fom_serv/cache/23.html, and *     Chuck Wilson supplied a patch involving dummy output registers.  See *     http://sourceforge.net/bugs/?func=detailbug&bug_id=108741&group_id=5624 *     for the original (anonymous) SourceForge bug report. * * 20000706: *  - Chuck Wilson passed along these remaining gcc 2.95.2 errors: *       pnggccrd.c: In function `png_combine_row': *       pnggccrd.c:525: more than 10 operands in `asm' *       pnggccrd.c:669: more than 10 operands in `asm' *       pnggccrd.c:828: more than 10 operands in `asm' *       pnggccrd.c:994: more than 10 operands in `asm' *       pnggccrd.c:1177: more than 10 operands in `asm' *     They are all the same problem and can be worked around by using the *     global _unmask variable unconditionally, not just in the -fPIC case. *     Reportedly earlier versions of gcc also have the problem with more than *     10 operands; they just don't report it.  Much strangeness ensues, etc. * * 20000729: *  - enabled png_read_filter_row_mmx_up() (shortest remaining unconverted *     MMX routine); began converting png_read_filter_row_mmx_sub() *  - to finish remaining sections: *     - clean up indentation and comments *     - preload local variables *     - add output and input regs (order of former determines numerical *        mapping of latter) *     - avoid all usage of ebx (including bx, bh, bl) register [20000823] *     - remove "$" from addressing of Shift and Mask variables [20000823] * * 20000731: *  - global union vars causing segfaults in png_read_filter_row_mmx_sub()? * * 20000822: *  - ARGH, stupid png_read_filter_row_mmx_sub() segfault only happens with *     shared-library (-fPIC) version!  Code works just fine as part of static *     library.  Damn damn damn damn damn, should have tested that sooner. *     ebx is getting clobbered again (explicitly this time); need to save it *     on stack or rewrite asm code to avoid using it altogether.  Blargh! * * 20000823: *  - first section was trickiest; all remaining sections have ebx -> edx now. *     (-fPIC works again.)  Also added missing underscores to various Shift* *     and *Mask* globals and got rid of leading "$" signs. * * 20000826: *  - added visual separators to help navigate microscopic printed copies *     (http://pobox.com/~newt/code/gpr-latest.zip, mode 10); started working *     on png_read_filter_row_mmx_avg() * * 20000828: *  - finished png_read_filter_row_mmx_avg():  only Paeth left! (930 lines...) *     What the hell, did png_read_filter_row_mmx_paeth(), too.  Comments not *     cleaned up/shortened in either routine, but functionality is complete *     and seems to be working fine. * * 20000829: *  - ahhh, figured out last(?) bit of gcc/gas asm-fu:  if register is listed *     as an input reg (with dummy output variables, etc.), then it *cannot* *     also appear in the clobber list or gcc 2.95.2 will barf.  The solution *     is simple enough... * * 20000914: *  - bug in png_read_filter_row_mmx_avg():  16-bit grayscale not handled *     correctly (but 48-bit RGB just fine) * * 20000916: *  - fixed bug in png_read_filter_row_mmx_avg(), bpp == 2 case; three errors: *     - "_ShiftBpp.use = 24;"      should have been   "_ShiftBpp.use = 16;" *     - "_ShiftRem.use = 40;"      should have been   "_ShiftRem.use = 48;" *     - "psllq _ShiftRem, %%mm2"   should have been   "psrlq _ShiftRem, %%mm2" * * 20010101: *  - added new png_init_mmx_flags() function (here only because it needs to *     call mmxsupport(), which should probably become global png_mmxsupport()); *     modified other MMX routines to run conditionally (png_ptr->asm_flags) * * 20010103: *  - renamed mmxsupport() to png_mmx_support(), with auto-set of mmx_supported, *     and made it public; moved png_init_mmx_flags() to png.c as internal func * * 20010104: *  - removed dependency on png_read_filter_row_c() (C code already duplicated *     within MMX version of png_read_filter_row()) so no longer necessary to *     compile it into pngrutil.o * * 20010310: *  - fixed buffer-overrun bug in png_combine_row() C code (non-MMX) * * 20020304: *  - eliminated incorrect use of width_mmx in pixel_bytes == 8 case * * 20040724: *   - more tinkering with clobber list at lines 4529 and 5033, to get *     it to compile on gcc-3.4. * * STILL TO DO: *     - test png_do_read_interlace() 64-bit case (pixel_bytes == 8) *     - write MMX code for 48-bit case (pixel_bytes == 6) *     - figure out what's up with 24-bit case (pixel_bytes == 3): *        why subtract 8 from width_mmx in the pass 4/5 case? *        (only width_mmx case) (near line 1606) *     - rewrite all MMX interlacing code so it's aligned with beginning *        of the row buffer, not the end (see 19991007 for details) *     x pick one version of mmxsupport() and get rid of the other *     - add error messages to any remaining bogus default cases *     - enable pixel_depth == 8 cases in png_read_filter_row()? (test speed) *     x add support for runtime enable/disable/query of various MMX routines */#define PNG_INTERNAL#include "png.h"#if defined(PNG_USE_PNGGCCRD)int PNGAPI png_mmx_support(void);#ifdef PNG_USE_LOCAL_ARRAYSstatic const int FARDATA png_pass_start[7] = {0, 4, 0, 2, 0, 1, 0};static const int FARDATA png_pass_inc[7]   = {8, 8, 4, 4, 2, 2, 1};static const int FARDATA png_pass_width[7] = {8, 4, 4, 2, 2, 1, 1};#endif#if defined(PNG_ASSEMBLER_CODE_SUPPORTED)/* djgpp, Win32, and Cygwin add their own underscores to global variables, * so define them without: */#if defined(__DJGPP__) || defined(WIN32) || defined(__CYGWIN__)#  define _mmx_supported  mmx_supported#  define _const4         const4#  define _const6         const6#  define _mask8_0        mask8_0#  define _mask16_1       mask16_1#  define _mask16_0       mask16_0#  define _mask24_2       mask24_2#  define _mask24_1       mask24_1#  define _mask24_0       mask24_0#  define _mask32_3       mask32_3#  define _mask32_2       mask32_2#  define _mask32_1       mask32_1#  define _mask32_0       mask32_0#  define _mask48_5       mask48_5#  define _mask48_4       mask48_4#  define _mask48_3       mask48_3#  define _mask48_2       mask48_2#  define _mask48_1       mask48_1#  define _mask48_0       mask48_0#  define _LBCarryMask    LBCarryMask#  define _HBClearMask    HBClearMask#  define _ActiveMask     ActiveMask#  define _ActiveMask2    ActiveMask2#  define _ActiveMaskEnd  ActiveMaskEnd#  define _ShiftBpp       ShiftBpp#  define _ShiftRem       ShiftRem#ifdef PNG_THREAD_UNSAFE_OK#  define _unmask         unmask#  define _FullLength     FullLength#  define _MMXLength      MMXLength#  define _dif            dif#  define _patemp         patemp#  define _pbtemp         pbtemp#  define _pctemp         pctemp#endif#endif/* These constants are used in the inlined MMX assembly code.   Ignore gcc's "At top level: defined but not used" warnings. *//* GRR 20000706:  originally _unmask was needed only when compiling with -fPIC, *  since that case uses the %ebx register for indexing the Global Offset Table *  and there were no other registers available.  But gcc 2.95 and later emit *  "more than 10 operands in `asm'" errors when %ebx is used to preload unmask *  in the non-PIC case, so we'll just use the global unconditionally now. */#ifdef PNG_THREAD_UNSAFE_OKstatic int _unmask;#endifstatic unsigned long long _mask8_0  = 0x0102040810204080LL;static unsigned long long _mask16_1 = 0x0101020204040808LL;static unsigned long long _mask16_0 = 0x1010202040408080LL;static unsigned long long _mask24_2 = 0x0101010202020404LL;static unsigned long long _mask24_1 = 0x0408080810101020LL;static unsigned long long _mask24_0 = 0x2020404040808080LL;static unsigned long long _mask32_3 = 0x0101010102020202LL;static unsigned long long _mask32_2 = 0x0404040408080808LL;static unsigned long long _mask32_1 = 0x1010101020202020LL;static unsigned long long _mask32_0 = 0x4040404080808080LL;static unsigned long long _mask48_5 = 0x0101010101010202LL;