format.txt

很少见的源码公开的msc51和z80的c编译器。

        2.5.1  Object Module Format 


           The  first  line  of  an object module contains the [XDQ][HL]
        format specifier (i.e.  XH indicates  a  hexidecimal  file  with
        most significant byte first) for the following designators.  


        2.5.2  Header Line 

                H aa areas gg global symbols 

           The  header  line  specifies  the number of areas(aa) and the
        number of global symbols(gg) defined or referenced in  this  ob-
        ject module segment.  


        2.5.3  Module Line 

                M name 

           The  module  line  specifies  the module name from which this
        header segment was assembled.  The module line will  not  appear
        if the .module directive was not used in the source program.  


        2.5.4  Symbol Line 

                S string Defnnnn 

                        or 

                S string Refnnnn 

           The  symbol line defines (Def) or references (Ref) the symbol
        'string' with the value nnnn.  The defined value is relative  to
        the  current  area  base  address.   References to constants and
        external global symbols will always appear before the first area
        definition.  References to external symbols will have a value of
        zero.  


        2.5.5  Area Line 

                A label size ss flags ff 

           The  area  line  defines the area label, the size (ss) of the
        area in bytes, and the area flags (ff).  The area flags  specify
        the ABS, REL, CON, OVR, and PAG parameters:  

                OVR/CON  (0x04/0x00 i.e.  bit position 2) 

                ABS/REL  (0x08/0x00 i.e.  bit position 3) 

                PAG      (0x10 i.e.  bit position 4) 


        2.5.6  T Line 

                T xx xx nn nn nn nn nn ...  

           The  T  line contains the assembled code output by the assem-
        bler with xx xx being the offset address from the  current  area
        base address and nn being the assembled instructions and data in
        byte format.  


        2.5.7  R Line 

                R 0 0 nn nn n1 [n1x]  n2 xx xx ...  

           The R line provides the relocation information to the linker.
        The nn nn value is the current area index, i.e.  which area  the
        current  values  were  assembled.  Relocation information is en-
        coded in groups of 4 (possibly 5) bytes:  

             1.  n1 (and optionally n1x) is the relocation mode and object
		 format:
                 1.  bit 0 word(0x00)/byte(0x01) 
                 2.  bit 1 relocatable area(0x00)/symbol(0x02) 
                 3.  bit 2 normal(0x00)/PC relative(0x04) relocation 
                 4.  bit 3  1-byte(0x00)/2-byte(0x08) object format for
                     byte data 
                 5.  bit 4 signed(0x00)/unsigned(0x10) byte data 
                 6.  bit 5 normal(0x00)/page '0'(0x20) reference 
                 7.  bit 6 normal(0x00)/page 'nnn'(0x40) reference 
                 8.  bit 7  LSB  byte(0x00)/MSB  byte(0x80) with 2-byte
                     mode
		 9.  bit 8  1 or 2  (0x00)/3-byte (0x100) object format
		     for byte data.
		 10. bit 9  LSB or MSB (middle byte) (0x00) or byte 3 
		     (real MSB) (0x200) for 3-byte mode.

		If the upper four bits of n1 are set (i.e. 
		(n1 & 0xf0) == 0xf0), it is taken as an escape character, 
		and the relocation mode will consist of the lower four bits
		of n1 left shifted 8 bits or'ed with the value of n1x. If
		the upper four bits of n1 are not all set, then it is not an 
		escape character, and the n1x byte is not present.

		This escape mechanism allows a 12-bit relocation mode value.

		Note that in byte mode, when 3-byte mode is used (bits 0
		and 8 are both set), the MSB bit (bit 7) really refers to 
		the 16 bit MSB (the middle byte of the 24-bit value) while
	        the "byte 3" bit (bit 9) refers to the 24-bit MSB.

             2.  n2  is  a byte index into the corresponding (i.e.  pre-
                 ceeding) T line data (i.e.  a pointer to the data to be
                 updated  by  the  relocation).   The T line data may be
                 1-byte or  2-byte  byte  data  format  or  2-byte  word
                 format.  

             3.  xx xx  is the area/symbol index for the area/symbol be-
                 ing referenced.  the corresponding area/symbol is found
                 in the header area/symbol lists.  


        The groups of 4 bytes are repeated for each item requiring relo-
        cation in the preceeding T line.  


        2.5.8  P Line 

                P 0 0 nn nn n1 n2 xx xx 

           The  P  line provides the paging information to the linker as
        specified by a .setdp directive.  The format of  the  relocation
        information is identical to that of the R line.  The correspond-
        ing T line has the following information:  
                T xx xx aa aa bb bb 

           Where  aa aa is the area reference number which specifies the
        selected page area and bb bb is the base address  of  the  page.
        bb bb will require relocation processing if the 'n1 n2 xx xx' is
        specified in the P line.  The linker will verify that  the  base
        address is on a 256 byte boundary and that the page length of an
        area defined with the PAG type is not larger than 256 bytes.  

           The  linker  defaults any direct page references to the first
        area defined in the input REL file.  All ASxxxx assemblers  will
        specify the _CODE area first, making this the default page area.