GDB 7.6.50

bfd/doc/mmo.texi

Index: bfd/doc/mmo.texi
diff --git a/bfd/doc/mmo.texi b/bfd/doc/mmo.texi
deleted file mode 100644
index b0d726aad9c1ec18672a21541f01861dab54c053..0000000000000000000000000000000000000000
--- a/bfd/doc/mmo.texi
+++ /dev/null
@@ -1,365 +0,0 @@
-@section mmo backend
-The mmo object format is used exclusively together with Professor
-Donald E.@: Knuth's educational 64-bit processor MMIX.  The simulator
-@command{mmix} which is available at
-@url{http://www-cs-faculty.stanford.edu/~knuth/programs/mmix.tar.gz}
-understands this format.  That package also includes a combined
-assembler and linker called @command{mmixal}.  The mmo format has
-no advantages feature-wise compared to e.g. ELF.  It is a simple
-non-relocatable object format with no support for archives or
-debugging information, except for symbol value information and
-line numbers (which is not yet implemented in BFD).  See
-@url{http://www-cs-faculty.stanford.edu/~knuth/mmix.html} for more
-information about MMIX.  The ELF format is used for intermediate
-object files in the BFD implementation.
-
-@c We want to xref the symbol table node.  A feature in "chew"
-@c requires that "commands" do not contain spaces in the
-@c arguments.  Hence the hyphen in "Symbol-table".
-@menu
-* File layout::
-* Symbol-table::
-* mmo section mapping::
-@end menu
-
-@node File layout, Symbol-table, mmo, mmo
-@subsection File layout
-The mmo file contents is not partitioned into named sections as
-with e.g.@: ELF.  Memory areas is formed by specifying the
-location of the data that follows.  Only the memory area
-@samp{0x0000@dots{}00} to @samp{0x01ff@dots{}ff} is executable, so
-it is used for code (and constants) and the area
-@samp{0x2000@dots{}00} to @samp{0x20ff@dots{}ff} is used for
-writable data.  @xref{mmo section mapping}.
-
-There is provision for specifying ``special data'' of 65536
-different types.  We use type 80 (decimal), arbitrarily chosen the
-same as the ELF @code{e_machine} number for MMIX, filling it with
-section information normally found in ELF objects. @xref{mmo
-section mapping}.
-
-Contents is entered as 32-bit words, xor:ed over previous
-contents, always zero-initialized.  A word that starts with the
-byte @samp{0x98} forms a command called a @samp{lopcode}, where
-the next byte distinguished between the thirteen lopcodes.  The
-two remaining bytes, called the @samp{Y} and @samp{Z} fields, or
-the @samp{YZ} field (a 16-bit big-endian number), are used for
-various purposes different for each lopcode.  As documented in
-@url{http://www-cs-faculty.stanford.edu/~knuth/mmixal-intro.ps.gz},
-the lopcodes are:
-
-@table @code
-@item lop_quote
-0x98000001.  The next word is contents, regardless of whether it
-starts with 0x98 or not.
-
-@item lop_loc
-0x9801YYZZ, where @samp{Z} is 1 or 2.  This is a location
-directive, setting the location for the next data to the next
-32-bit word (for @math{Z = 1}) or 64-bit word (for @math{Z = 2}),
-plus @math{Y * 2^56}.  Normally @samp{Y} is 0 for the text segment
-and 2 for the data segment.
-
-@item lop_skip
-0x9802YYZZ.  Increase the current location by @samp{YZ} bytes.
-
-@item lop_fixo
-0x9803YYZZ, where @samp{Z} is 1 or 2.  Store the current location
-as 64 bits into the location pointed to by the next 32-bit
-(@math{Z = 1}) or 64-bit (@math{Z = 2}) word, plus @math{Y *
-2^56}.
-
-@item lop_fixr
-0x9804YYZZ.  @samp{YZ} is stored into the current location plus
-@math{2 - 4 * YZ}.
-
-@item lop_fixrx
-0x980500ZZ.  @samp{Z} is 16 or 24.  A value @samp{L} derived from
-the following 32-bit word are used in a manner similar to
-@samp{YZ} in lop_fixr: it is xor:ed into the current location
-minus @math{4 * L}.  The first byte of the word is 0 or 1.  If it
-is 1, then @math{L = (@var{lowest 24 bits of word}) - 2^Z}, if 0,
-then @math{L = (@var{lowest 24 bits of word})}.
-
-@item lop_file
-0x9806YYZZ.  @samp{Y} is the file number, @samp{Z} is count of
-32-bit words.  Set the file number to @samp{Y} and the line
-counter to 0.  The next @math{Z * 4} bytes contain the file name,
-padded with zeros if the count is not a multiple of four.  The
-same @samp{Y} may occur multiple times, but @samp{Z} must be 0 for
-all but the first occurrence.
-
-@item lop_line
-0x9807YYZZ.  @samp{YZ} is the line number.  Together with
-lop_file, it forms the source location for the next 32-bit word.
-Note that for each non-lopcode 32-bit word, line numbers are
-assumed incremented by one.
-
-@item lop_spec
-0x9808YYZZ.  @samp{YZ} is the type number.  Data until the next
-lopcode other than lop_quote forms special data of type @samp{YZ}.
-@xref{mmo section mapping}.
-
-Other types than 80, (or type 80 with a content that does not
-parse) is stored in sections named @code{.MMIX.spec_data.@var{n}}
-where @var{n} is the @samp{YZ}-type.  The flags for such a
-sections say not to allocate or load the data.  The vma is 0.
-Contents of multiple occurrences of special data @var{n} is
-concatenated to the data of the previous lop_spec @var{n}s.  The
-location in data or code at which the lop_spec occurred is lost.
-
-@item lop_pre
-0x980901ZZ.  The first lopcode in a file.  The @samp{Z} field forms the
-length of header information in 32-bit words, where the first word
-tells the time in seconds since @samp{00:00:00 GMT Jan 1 1970}.
-
-@item lop_post
-0x980a00ZZ.  @math{Z > 32}.  This lopcode follows after all
-content-generating lopcodes in a program.  The @samp{Z} field
-denotes the value of @samp{rG} at the beginning of the program.
-The following @math{256 - Z} big-endian 64-bit words are loaded
-into global registers @samp{$G} @dots{} @samp{$255}.
-
-@item lop_stab
-0x980b0000.  The next-to-last lopcode in a program.  Must follow
-immediately after the lop_post lopcode and its data.  After this
-lopcode follows all symbols in a compressed format
-(@pxref{Symbol-table}).
-
-@item lop_end
-0x980cYYZZ.  The last lopcode in a program.  It must follow the
-lop_stab lopcode and its data.  The @samp{YZ} field contains the
-number of 32-bit words of symbol table information after the
-preceding lop_stab lopcode.
-@end table
-
-Note that the lopcode "fixups"; @code{lop_fixr}, @code{lop_fixrx} and
-@code{lop_fixo} are not generated by BFD, but are handled.  They are
-generated by @code{mmixal}.
-
-This trivial one-label, one-instruction file:
-
-@example
- :Main TRAP 1,2,3
-@end example
-
-can be represented this way in mmo:
-
-@example
- 0x98090101 - lop_pre, one 32-bit word with timestamp.
- <timestamp>
- 0x98010002 - lop_loc, text segment, using a 64-bit address.
-              Note that mmixal does not emit this for the file above.
- 0x00000000 - Address, high 32 bits.
- 0x00000000 - Address, low 32 bits.
- 0x98060002 - lop_file, 2 32-bit words for file-name.
- 0x74657374 - "test"
- 0x2e730000 - ".s\0\0"
- 0x98070001 - lop_line, line 1.
- 0x00010203 - TRAP 1,2,3
- 0x980a00ff - lop_post, setting $255 to 0.
- 0x00000000
- 0x00000000
- 0x980b0000 - lop_stab for ":Main" = 0, serial 1.
- 0x203a4040   @xref{Symbol-table}.
- 0x10404020
- 0x4d206120
- 0x69016e00
- 0x81000000
- 0x980c0005 - lop_end; symbol table contained five 32-bit words.
-@end example
-@node Symbol-table, mmo section mapping, File layout, mmo
-@subsection Symbol table format
-From mmixal.w (or really, the generated mmixal.tex) in
-@url{http://www-cs-faculty.stanford.edu/~knuth/programs/mmix.tar.gz}):
-``Symbols are stored and retrieved by means of a @samp{ternary
-search trie}, following ideas of Bentley and Sedgewick. (See
-ACM--SIAM Symp.@: on Discrete Algorithms @samp{8} (1997), 360--369;
-R.@:Sedgewick, @samp{Algorithms in C} (Reading, Mass.@:
-Addison--Wesley, 1998), @samp{15.4}.)  Each trie node stores a
-character, and there are branches to subtries for the cases where
-a given character is less than, equal to, or greater than the
-character in the trie.  There also is a pointer to a symbol table
-entry if a symbol ends at the current node.''
-
-So it's a tree encoded as a stream of bytes.  The stream of bytes
-acts on a single virtual global symbol, adding and removing
-characters and signalling complete symbol points.  Here, we read
-the stream and create symbols at the completion points.
-
-First, there's a control byte @code{m}.  If any of the listed bits
-in @code{m} is nonzero, we execute what stands at the right, in
-the listed order:
-
-@example
- (MMO3_LEFT)
- 0x40 - Traverse left trie.
-        (Read a new command byte and recurse.)
-
- (MMO3_SYMBITS)
- 0x2f - Read the next byte as a character and store it in the
-        current character position; increment character position.
-        Test the bits of @code{m}:
-
-        (MMO3_WCHAR)
-        0x80 - The character is 16-bit (so read another byte,
-               merge into current character.
-
-        (MMO3_TYPEBITS)
-        0xf  - We have a complete symbol; parse the type, value
-               and serial number and do what should be done
-               with a symbol.  The type and length information
-               is in j = (m & 0xf).
-
-               (MMO3_REGQUAL_BITS)
-               j == 0xf: A register variable.  The following
-                         byte tells which register.
-               j <= 8:   An absolute symbol.  Read j bytes as the
-                         big-endian number the symbol equals.
-                         A j = 2 with two zero bytes denotes an
-                         unknown symbol.
-               j > 8:    As with j <= 8, but add (0x20 << 56)
-                         to the value in the following j - 8
-                         bytes.
-
-               Then comes the serial number, as a variant of
-               uleb128, but better named ubeb128:
-               Read bytes and shift the previous value left 7
-               (multiply by 128).  Add in the new byte, repeat
-               until a byte has bit 7 set.  The serial number
-               is the computed value minus 128.
-
-        (MMO3_MIDDLE)
-        0x20 - Traverse middle trie.  (Read a new command byte
-               and recurse.)  Decrement character position.
-
- (MMO3_RIGHT)
- 0x10 - Traverse right trie.  (Read a new command byte and
-        recurse.)
-@end example
-
-Let's look again at the @code{lop_stab} for the trivial file
-(@pxref{File layout}).
-
-@example
- 0x980b0000 - lop_stab for ":Main" = 0, serial 1.
- 0x203a4040
- 0x10404020
- 0x4d206120
- 0x69016e00
- 0x81000000
-@end example
-
-This forms the trivial trie (note that the path between ``:'' and
-``M'' is redundant):
-
-@example
- 203a     ":"
- 40       /
- 40      /
- 10      \
- 40      /
- 40     /
- 204d  "M"
- 2061  "a"
- 2069  "i"
- 016e  "n" is the last character in a full symbol, and
-       with a value represented in one byte.
- 00    The value is 0.
- 81    The serial number is 1.
-@end example
-
-@node mmo section mapping, , Symbol-table, mmo
-@subsection mmo section mapping
-The implementation in BFD uses special data type 80 (decimal) to
-encapsulate and describe named sections, containing e.g.@: debug
-information.  If needed, any datum in the encapsulation will be
-quoted using lop_quote.  First comes a 32-bit word holding the
-number of 32-bit words containing the zero-terminated zero-padded
-segment name.  After the name there's a 32-bit word holding flags
-describing the section type.  Then comes a 64-bit big-endian word
-with the section length (in bytes), then another with the section
-start address.  Depending on the type of section, the contents
-might follow, zero-padded to 32-bit boundary.  For a loadable
-section (such as data or code), the contents might follow at some
-later point, not necessarily immediately, as a lop_loc with the
-same start address as in the section description, followed by the
-contents.  This in effect forms a descriptor that must be emitted
-before the actual contents.  Sections described this way must not
-overlap.
-
-For areas that don't have such descriptors, synthetic sections are
-formed by BFD.  Consecutive contents in the two memory areas
-@samp{0x0000@dots{}00} to @samp{0x01ff@dots{}ff} and
-@samp{0x2000@dots{}00} to @samp{0x20ff@dots{}ff} are entered in
-sections named @code{.text} and @code{.data} respectively.  If an area
-is not otherwise described, but would together with a neighboring
-lower area be less than @samp{0x40000000} bytes long, it is joined
-with the lower area and the gap is zero-filled.  For other cases,
-a new section is formed, named @code{.MMIX.sec.@var{n}}.  Here,
-@var{n} is a number, a running count through the mmo file,
-starting at 0.
-
-A loadable section specified as:
-
-@example
- .section secname,"ax"
- TETRA 1,2,3,4,-1,-2009
- BYTE 80
-@end example
-
-and linked to address @samp{0x4}, is represented by the sequence:
-
-@example
- 0x98080050 - lop_spec 80
- 0x00000002 - two 32-bit words for the section name
- 0x7365636e - "secn"
- 0x616d6500 - "ame\0"
- 0x00000033 - flags CODE, READONLY, LOAD, ALLOC
- 0x00000000 - high 32 bits of section length
- 0x0000001c - section length is 28 bytes; 6 * 4 + 1 + alignment to 32 bits
- 0x00000000 - high 32 bits of section address
- 0x00000004 - section address is 4
- 0x98010002 - 64 bits with address of following data
- 0x00000000 - high 32 bits of address
- 0x00000004 - low 32 bits: data starts at address 4
- 0x00000001 - 1
- 0x00000002 - 2
- 0x00000003 - 3
- 0x00000004 - 4
- 0xffffffff - -1
- 0xfffff827 - -2009
- 0x50000000 - 80 as a byte, padded with zeros.
-@end example
-
-Note that the lop_spec wrapping does not include the section
-contents.  Compare this to a non-loaded section specified as:
-
-@example
- .section thirdsec
- TETRA 200001,100002
- BYTE 38,40
-@end example
-
-This, when linked to address @samp{0x200000000000001c}, is
-represented by:
-
-@example
- 0x98080050 - lop_spec 80
- 0x00000002 - two 32-bit words for the section name
- 0x7365636e - "thir"
- 0x616d6500 - "dsec"
- 0x00000010 - flag READONLY
- 0x00000000 - high 32 bits of section length
- 0x0000000c - section length is 12 bytes; 2 * 4 + 2 + alignment to 32 bits
- 0x20000000 - high 32 bits of address
- 0x0000001c - low 32 bits of address 0x200000000000001c
- 0x00030d41 - 200001
- 0x000186a2 - 100002
- 0x26280000 - 38, 40 as bytes, padded with zeros
-@end example
-
-For the latter example, the section contents must not be
-loaded in memory, and is therefore specified as part of the
-special data.  The address is usually unimportant but might
-provide information for e.g.@: the DWARF 2 debugging format.