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diff --git a/rdoff/v1/rdoff.txt b/rdoff/v1/rdoff.txt deleted file mode 100644 index 7ee86d6..0000000 --- a/rdoff/v1/rdoff.txt +++ /dev/null @@ -1,114 +0,0 @@ -The RDOFF version 1.1 Object File Format -======================================== - -I seem to keep writing this document... I don't know what keeps -happening to it. Anyway, this one will hopefully stay around for a -while. - -RDOFF is a relocatable object file format whose design goals were -mainly to keep it simple, so that an RDOFF object can be loaded and -executed by a very small piece of code (primarily so that it can be -used by the microkernel of an operating system to store system -modules, which can then go on to load and execute more complex object -files, eg ELF, if so desired), yet still be able to be cope with -everything required by the operating system; linkage of multiple -modules together (possibly with automatic loading of new libraries -that are referred to by the object) at load time, allowing static or -dynamic linking as required by the application. - -The overall format of the file is summarised in this table: - -Length (bytes) Description - 6 Contains the string 'RDOFF1' (little-endian targets), - or 'RDOFF' followed by the single byte 0x01 - (big-endian targets). - 4 Length of the header section - ? Header section (see above for length) - 4 Length of code section (.text) - ? Code section - 4 Length of data section (.data) - ? Data section - -Segments are referred to as numbers. Imported labels are implicitly -at offset zero from a segment; each is assigned a segment number when -it is imported. Segments in the object file itself are numbered: - 0 - text segemnt - 1 - data segment - 2 - bss segment - -The header consists of a sequence of records, each of which is -preceded by a byte to represent its type. - -These records are one of the following types: - -1: Relocation Record --------------------- - - This record points to an address that will need either - relocation or linkage to an external segment when the object - is loaded or linked. - - Length Description - 1 Type identifier (must be 1) - 1 Segment number (0 or 1) plus 64 if the reference is - relative (and thus does not require relocation with - the base of the code, only by the difference between - the start of this segment, and the segment referred to - (see below) - 4 Offset from start of segment of item requiring reloc. - 1 Length of item (1, 2, or 4 bytes...) - 2 Segment number to which reference is made. - -2: Import Symbol Record ------------------------ - - This record defines a segment to start at the location of a - named symbol; this symbol may need to be fetched from an - external library. - - Length Description - 1 Type identifier (must be 2) - 2 Segment number to allocate - ? String containing label (null terminated, max length = - 32 chars) - -3: Export Symbol Record ------------------------ - - This record defines a symbol, to which external modules can - link using the above record type. - - Length Description - 1 Type identifier (must be 3) - 1 Segment containing symbol (0,1 or 2) - 4 Offset of symbol within segment - ? String containing label (null terminated, max length = - 32 chars) - -4: Import Library Record ------------------------- - - This record tells the loader that an extra library should be - loaded and linked to the module at either load- or run-time - (load time is easier, run-time is good, though...) - - Length Description - 1 Type identifier (must be 4) - ? Name of library (null terminated string, max len = 128) - -5: Reserve BSS Bytes --------------------- - - This record tells the loader how much memory to reserve after - the executable code loaded from the object file for the BSS - segment (referred to as segment number 2). - A loader can safely assume that there will only be one of - these records per module, but the linker probably cannot... - NASM will only output one, but other utilities may be written - that do, and future versions of NASM may output more than one. - - Length Description - 1 Type identifier (must be 5) - 4 Number of bytes to reserve - - |