doc/services.txt

   1 SYSTEM SERVICES LAYOUT
   2 ======================
   3
   4 All  OS functionality  can be reached from one  or  several
   5 interfaces/services.
   6
   7 When calling the  system interrupt  0x32,  you request a service
   8 number and function in AX register with AL & AH. Making 256 the max
   9 number of interfaces and available service-functions.
  10
  11 Services numbered 0x0F and below are system reserved and will not be
  12 assigned automatically when requesting to add a new service. They can
  13 still be replaced by implicitly requesting that service number instead
  14 of getting a free one assigned.
  15
  16 This will allow for great OS modularity when each interface/service-
  17 group can be replaced or upgraded by any user software or driver.
  18
  19 Most service groups or interfaces can be extended with drivers for
  20 the type of device(s) that it handles, or the full service/interface
  21 can be replaced for more fundamental changes to the design. For
  22 example the 'process' and 'memory' interfaces can be replaced to
  23 allow more advanced functionality like multitasking and paging.
  24
  25 The OS will be unable to function at all without the basic service
  26 0x00 that performs the most crucial tasks, and without the STDIO and
  27 VFS interfaces it will be severly crippled, left with no means of
  28 communication, except perhaps a beep or two from the PC-speaker.
  29
  30 Below is a more visual representation of the main OS services
  31 that will likely be included in the kernel. And a draft of what
  32 functions each could or would include.  Some functions also have
  33 a breif example of parameters required.
  34
  35 Possible funture service groups or interfaces that could be system
  36 default include:
  37 - network functionality
  38 - general PCI devices
  39 - special one for all things USB?
  40 - GUI specific functions
  41 - running stuff in 16 and 64 bit, with extra DOS emulation
  42   and/or other services
  43
  44
  45
  46
  47 services.asm  (main service 0x00)
  48 --------------------------------------
  49   always present in BOS, kernel
  50 --------------------------------------
  51    - add service
  52         signature       dd  'VFS ', 'IO  ', 'SND ', 'PCI '
  53         version         db  1
  54         requested_no    db  23    ; 0xFF or 0x00 to get assigned
  55         service_struct  dd  0     ; memory address of service calltable
  56    - get servide
  57         AL = number
  58         returns all info above if service found
  59    - remove service
  60         AL = number
  61         removes / unloads a service/interface
  62    - get free number
  63         AL = free service number  ; always above 0x0F (below reserved)
  64    - get BOS version (and other misc. kernel functions below)
  65    - get/set interrupts
  66    - execute kernel monitor command/script
  67    - get time/date
  68    - DMA functions, here or in VFS/floppy/memory drivers?
  69    - GDT function, create new segments 'n shit
  70    - pc-speaker beep if not even stdio is found
  71    - CMOS / PIC functions
  72    - run 16/64 bit code - seperate services for this? (int21h included?)
  73    - get specified...
  74
  75
  76 stdio.asm (service number 0x01)
  77 --------------------------------------
  78   needs to init itself as a service,
  79   requesting servicenumber 1.
  80   internal struct with info on
  81   default in and out devices.
  82 --------------------------------------
  83    - add device
  84         type            db  1        ; 0 = output, 1 = input
  85         signature       dd  'COM ', 'VGA ', 'VESA', 'FILE', 'NET ', 'USB ', 'KEYB', 'MICE'
  86         version         db  1
  87         device_struct   dd  0     ; address of calltable
  88    - get device
  89         AL = assigned device type ID / 0 for default?
  90         returns all info above
  91    - remove device
  92         AL = assigned device type ID
  93         removes device
  94    - set default
  95         AL = assigned device type ID
  96         AH = 1 for in, 0 for out
  97    - getc
  98         get a char from stdin or specified device
  99    - putc
 100         put a char to stdout or specified device
 101
 102    .... other default stubs needed for STDIO ....
 103
 104
 105 vfs.asm (service number 0x02)
 106 --------------------------------------
 107   needs to init itself as a service,
 108   requesting servicenumber 2.
 109   internal struct with info on
 110   devices and filesystems.
 111   add simple 'FILE' STDIO interface?
 112 --------------------------------------
 113    - add device
 114    - remove device
 115    - get devices (list or number specified)
 116    - read sector
 117    - write sector
 118    - seek
 119    - more device specific stubs?
 120    ...
 121    - add fs
 122    - remove fs
 123    - parse path
 124    - load file
 125    - write file
 126    - seek file
 127    - close file
 128    - mount device (with auto detect fs option)
 129    - format fs (take device argument)
 130    - more fs specific stubs?
 131
 132
 133 proccess.asm (service number 0x03)
 134 --------------------------------------
 135   needs to init itself as a service,
 136   requesting servicenumber 3.
 137   possible to extend/replace for
 138   multitasking.
 139 --------------------------------------
 140    - Load process
 141        needs VFS info to load file
 142    - Exit process
 143    - Terminate and Stay Resident
 144    - Add exec. driver
 145        interface to load driver/extensions for
 146        more executable formats, possibly other
 147        execution modes: realmode, longmode
 148    - Remove driver
 149
 150
 151 memory.asm (service number 0x04)
 152 --------------------------------------
 153   needs to init itself as a service,
 154   requesting servicenumber 4.
 155 --------------------------------------
 156    - lowalloc ? (for low mem, DMA & 16bit code)
 157    - alloc
 158    - realloc
 159    - free
 160    - DMA functions here? Possibly most related to mem?