Leaked source code of windows server 2003
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;-------------------------------------------------------------------------;; FILE : ORIGIN.INC;; This is included in origin.asm and mshead.asm. Contains the equate that; is used for ORGing the DOS code.;; Brief Description of the necessacity of this ORG:; -------------------------------------------------;; A special problem exits when running out of the HMA. The HMA starts at ; address FFFF:10. There is no place in the HMA with an offset of zero.; This means programs running out off the HMA must use non-zero offset base; addresses. It also means that if we're running multiple programs from the; HMA, the base offset of each segment must atleast be as big as all of the; HMA segments that precede it.; ; One solution to this problem to ORG each module at 64K minus its size.; For instance a code segment 1234h bytes in length would org'd at edcbh.; This gives max. flexibility regarding it's location in the HMA. By ; selecting segment values between f124h and ffffh it could be located ; anywhere in the HMA. The problem with this is that programs with such ; high ORGs would not be able to run in low RAM.;; A comporomise solution is to set the ORG address somewhere between 0010h; and ffffh - their size. In the particular case of the BIOS and the DOS ; the folloowing solution has been implemented:;; The Bios Code segment will have a very small offset and run at the very; front of the HMA, after the VDISK header. THE Dos Code segment will have ; a base offset of (700+<min. size off RAM based BIOS>+<min. size of the DOS; DATA segment when DOS is running low>). This will reflect the lowest ; possible physical address at which DOS code will run, while still providing; max. possible flexibility in HMA positioning. This offset MUST NOT be ; smaller then that 20+size of Bios Code segment when running high. This is ; mostly true.;; Also this ORG'd value must be communicated to the BIOS. This is done by; putting this value after the first jmp instruction in the DOS code in; mshead.asm. ;; In order for the stripz utility to know how many zeroes to be stripped ; out, this value is placed at the beginning of the binary in origin.asm.;; Revision History:;; Currently this is being done manually. Therefore any change in the DOS DATA; Size or the BIOS size should be reflected here. --- Feb 90;; BDSIZE.INC contains the equates for BIODATASIZE, BIOCODESIZ and DOSDATASIZ.; A utility called getsize will obtain the corresponding values from msdos; and msbio.map and update the values in BDSIZ.INC if they are different. ; DOS should now be built using the batch file makedos.bat which invokes this; utility. The FORMAT of BDSIZE.INC should not be changed as getsize is ; dependant on that. --- Apr 3 '90;; For ROMDOS, however, there is no need to org the doscode to any location; other than zero. Therefore the stripz utility will not need to be used,; so the offset will not need to be included at the beginning of the code; segment. Also, the BIOS can just assume that the resident code begins; at offset zero within the segment.; ;;-------------------------------------------------------------------------- ;
BIODATASTART EQU 00700hinclude bdsize.inc ; this sets the values: ; BIODATASIZ ; BIOCODESIZ ; DOSDATASIZ
ifndef NEC_98BYTSTART EQU BIODATASTART+BIODATASIZ+BIOCODESIZ+DOSDATASIZPARASTART EQU ((BYTSTART + 0FH) AND (NOT 0FH)) - 40helse ;NEC_98BYTSTART EQU BIOCODESIZPARASTART EQU (BYTSTART + 0FH) AND (NOT 0FH) endif ;NEC_98
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