URL
https://opencores.org/ocsvn/eco32/eco32/trunk
Subversion Repositories eco32
Compare Revisions
- This comparison shows the changes necessary to convert path
/eco32/tags/eco32-0.25/binutils/include
- from Rev 115 to Rev 248
- ↔ Reverse comparison
Rev 115 → Rev 248
/ar.h
0,0 → 1,28
/* |
* ar.h -- structure of archives (object libraries) |
*/ |
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#ifndef _AR_H_ |
#define _AR_H_ |
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#define AR_MAGIC 0x0412CF03 /* archive file magic number */ |
#define MAX_NAME 60 /* max length of member name */ |
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/* |
* The following structure is stored once per archive member. |
*/ |
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typedef struct { |
char name[MAX_NAME]; |
time_t date; |
int uid; |
int gid; |
int mode; |
long size; |
} ArHeader; |
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#endif /* _AR_H_ */ |
/a.out.h
0,0 → 1,52
/* |
* a.out.h -- structure of linkable object and executable files |
*/ |
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#ifndef _A_OUT_H_ |
#define _A_OUT_H_ |
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#define EXEC_MAGIC 0x1AA09232 |
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#define METHOD_H16 0 /* write 16 bits with high part of value */ |
#define METHOD_L16 1 /* write 16 bits with low part of value */ |
#define METHOD_R16 2 /* write 16 bits with value relative to PC */ |
#define METHOD_R26 3 /* write 26 bits with value relative to PC */ |
#define METHOD_W32 4 /* write full 32 bit word with value */ |
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#define SEGMENT_ABS 0 /* absolute values */ |
#define SEGMENT_CODE 1 /* code segment */ |
#define SEGMENT_DATA 2 /* initialized data segment */ |
#define SEGMENT_BSS 3 /* uninitialized data segment */ |
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typedef struct { |
unsigned int magic; /* must be EXEC_MAGIC */ |
unsigned int csize; /* size of code in bytes */ |
unsigned int dsize; /* size of initialized data in bytes */ |
unsigned int bsize; /* size of uninitialized data in bytes */ |
unsigned int crsize; /* size of code relocation info in bytes */ |
unsigned int drsize; /* size of data relocation info in bytes */ |
unsigned int symsize; /* size of symbol table in bytes */ |
unsigned int strsize; /* size of string space in bytes */ |
} ExecHeader; |
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typedef struct { |
unsigned int offset; /* where to relocate */ |
int method; /* how to relocate */ |
int value; /* additive part of value */ |
int base; /* if MSB = 0: segment number */ |
/* if MSB = 1: symbol table index */ |
} RelocRecord; |
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typedef struct { |
unsigned int name; /* offset in string space */ |
int type; /* if MSB = 0: the symbol's segment */ |
/* if MSB = 1: the symbol is undefined */ |
int value; /* if symbol defined: the symbol's value */ |
/* if symbol not defined: meaningless */ |
} SymbolRecord; |
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#endif /* _A_OUT_H_ */ |
/README
0,0 → 1,162
|
Format of Object and Executable Files |
------------------------------------- |
|
0) General |
|
The "a.out" file format is used as format for assembler output |
("object files") as well as for linker output ("executable files"). |
The difference of these two is the size of certain sections of |
the file being zero in case of executable files. |
|
The file consists of a header and up to 6 sections: |
- code |
- initialized data |
- code relocation records |
- data relocation records |
- symbol table records |
- symbol string storage |
|
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1) Header |
|
The header specifies the sizes of all following sections, |
but has itself a fixed length (and is always present): |
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typedef struct { |
unsigned int magic; /* must be EXEC_MAGIC */ |
unsigned int csize; /* size of code in bytes */ |
unsigned int dsize; /* size of initialized data in bytes */ |
unsigned int bsize; /* size of uninitialized data in bytes */ |
unsigned int crsize; /* size of code relocation info in bytes */ |
unsigned int drsize; /* size of data relocation info in bytes */ |
unsigned int symsize; /* size of symbol table in bytes */ |
unsigned int strsize; /* size of string space in bytes */ |
} ExecHeader; |
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The magic number is used to distinguish executable files from |
other file types. This field must have the value EXEC_MAGIC. |
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The code size is given in bytes, but is always a multiple of 4. |
This is the exact size of the code section in the executable file. |
For the code size in memory see "executing an executable" below. |
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The initialized data size is given in bytes, but is always a |
multiple of 4. This is the exact size of the initialized data |
section in the executable file. For the data size in memory see |
"executing an executable" below. |
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The uninitialized data size is given in bytes, but is always a |
multiple of 4. There is no corresponding section to this value |
contained within the executable. See "executing an executable" |
below for the semantics of this value. |
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The code relocation info size is given in bytes, but is always |
a multiple of sizeof(RelocRecord). These records describe the |
changes to be applied to the code section during the link step. |
This size is zero if the file is an executable. |
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The data relocation info size is given in bytes, but is always |
a multiple of sizeof(RelocRecord). These records describe the |
changes to be applied to the data section during the link step. |
This size is zero if the file is an executable. |
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The size of the symbol table is given in bytes, but is always |
a multiple of sizeof(SymbolRecord). The symbol table contains |
information about symbols which are exported from or imported |
into this object file. It is mainly used during the link step |
and may not be present (size = 0) if the file is an executable. |
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The string space is used to store the names of the symbols in |
the symbol table. |
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2) Code/Initialized Data |
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These sections contain the instructions and the initialized data |
of the program, respectively. |
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3) Code/Data Relocation Records |
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The relocation records have the following structure: |
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typedef struct { |
unsigned int offset; /* where to relocate */ |
int method; /* how to relocate */ |
int value; /* additive part of value */ |
int base; /* if MSB = 0: segment number */ |
/* if MSB = 1: symbol table index */ |
} RelocRecord; |
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The offset gives the position where the relocation has to be done, |
in the form of a byte offset from the beginning of the section. |
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The method determines how the relocation is performed, and must |
be one of the following constants: |
METHOD_H16 /* write 16 bits with high part of value */ |
METHOD_L16 /* write 16 bits with low part of value */ |
METHOD_R16 /* write 16 bits with value relative to PC */ |
METHOD_R26 /* write 26 bits with value relative to PC */ |
METHOD_W32 /* write full 32 bit word with value */ |
|
"Value" and "base" together are used to compute the final value of |
the relocated code or data item. The value is added to the value of |
the base. The base is either the start address of a segment in memory, |
or the value of an imported symbol. In the former case, which is marked |
by an MSB of 0, the base is specified as one of the following constants: |
SEGMENT_ABS /* absolute values */ |
SEGMENT_CODE /* code segment */ |
SEGMENT_DATA /* initialized data segment */ |
SEGMENT_BSS /* uninitialized data segment */ |
In the latter case, which is marked by an MSB of 1, the remaining bits |
specify the index of the symbol in the symbol table. |
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4) Symbol Table Records |
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For every symbol which is imported into or exported from the current |
object file, there is a corresponding symbol table record: |
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typedef struct { |
unsigned int name; /* offset in string space */ |
int type; /* if MSB = 0: the symbol's segment */ |
/* if MSB = 1: the symbol is undefined */ |
int value; /* if symbol defined: the symbol's value */ |
/* if symbol not defined: meaningless */ |
} SymbolRecord; |
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The name of the symbol is given as an offset into the string space. |
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If the "type" has an MSB of 0, the symbol is defined here (i.e., |
it is exported), and the "type" specifies the segment (for the |
segment constants see above) in which the symbol is defined, while |
the "value" holds its value. Otherwise, the symbol is not defined |
here (i.e., it is imported), and the "value" has no meaning. |
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5) Symbol String Storage |
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The strings are null-terminated and stored without any padding. |
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6) Executing an Executable |
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When an executable file is loaded into memory for execution, three |
logical segments are set up: the code segment, the data segment (with |
initialized data, followed by uninitialized data, which starts off |
as all 0), and a stack. |
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The code segment begins at address 0 in virtual memory and is loaded |
with the contents of the code section from the executable file. |
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The data segment begins at the next page boundary (multiple of 4 KB) |
after the code segment. It is loaded with the contents of the data |
section from the executable file and is followed immediately by the |
"uninitialized data", which must be zeroed by the loader. The data |
area is expanded upwards as requested by explicit "brk" system calls. |
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The stack is located in the highest possible locations in the virtual |
address space, which are accessible in user mode, and thus expanding |
downwards from (but excluding) the address 0x80000000. It is extended |
automatically by the operating system. |