kernel/fdc/dma.asm

   1 ;----------------------------------------------------------;
   2 ; BOS kernel                Christoffer Bubach, 2004-2005. ;
   3 ;----------------------------------------------------------;
   4 ;                                                          ;
   5 ;    DMA transfer code.                                    ;
   6 ;                                                          ;
   7 ;----------------------------------------------------------;
   8
   9
  10 ;------------------------------------------;
  11 ;  Lookup table for DMA controller ports   ;
  12 ;------------------------------------------;
  13      dma_mask_reg    dw   0x0A, 0x0A, 0x0A, 0x0A, 0xD4, 0xD4, 0xD4, 0xD4
  14      dma_mode_reg    dw   0x0B, 0x0B, 0x0B, 0x0B, 0xD6, 0xD6, 0xD6, 0xD6
  15      dma_clear_reg   dw   0x0C, 0x0C, 0x0C, 0x0C, 0xD8, 0xD8, 0xD8, 0xD8
  16      dma_page_port   dw   0x87, 0x83, 0x81, 0x82, 0x8F, 0x8B, 0x89, 0x8A
  17      dma_addr_port   dw   0x00, 0x02, 0x04, 0x06, 0xC0, 0xC4, 0xC8, 0xCC
  18      dma_count_port  dw   0x01, 0x03, 0x05, 0x07, 0xC2, 0xC6, 0xCA, 0xCE
  19
  20
  21 ;-----------------------------------;
  22 ;   dma transfer                    ;
  23 ;                                   ;
  24 ;  in:  ecx = page:offset           ;
  25 ;       bl  = channel               ;
  26 ;       bh  = 1=read, 0=write       ;
  27 ;       esi = count                 ;
  28 ;                                   ;
  29 ;  out: nothing.                    ;
  30 ;-----------------------------------;
  31 dma_transfer:
  32         push   eax
  33         push   edx
  34         push   esi
  35         cli
  36         or     bh, bh
  37         jz     .dont_read
  38
  39         mov    bh, bl
  40         add    bh, 0x48
  41         jmp    .read
  42     .dont_read:
  43         mov    bh, bl
  44         add    bh, 0x44
  45     .read:
  46         dec    esi
  47
  48         movzx  eax, bl
  49         mov    dx, word [(eax*2)+dma_mask_reg]
  50         mov    al, bl
  51         or     al, 0x04
  52         out    dx, al                                 ; disable the channel
  53
  54         movzx  eax, bl
  55         mov    dx, word [(eax*2)+dma_clear_reg]
  56         mov    al, 0
  57         out    dx, al                                 ; initialize flip-flop
  58
  59         movzx  eax, bl
  60         mov    dx, word [(eax*2)+dma_mode_reg]
  61         mov    al, bh
  62         out    dx, al                                 ; set DMA mode
  63
  64         movzx  eax, bl
  65         mov    dx, word [(eax*2)+dma_addr_port]
  66         mov    al, cl
  67         out    dx, al                                 ; write low offset part
  68         mov    al, ch
  69         out    dx, al                                 ; and high offset part
  70
  71         movzx  eax, bl
  72         mov    dx, word [(eax*2)+dma_page_port]
  73         mov    eax, ecx
  74         shr    eax, 16
  75         out    dx, al                                 ; write page.
  76
  77         movzx  eax, bl
  78         mov    dx, word [(eax*2)+dma_count_port]
  79         mov    eax, esi
  80         out    dx, al                                 ; low count
  81         mov    al, ah
  82         out    dx, al                                 ; high count
  83
  84         movzx  eax, bl
  85         mov    dx, word [(eax*2)+dma_mask_reg]
  86         mov    al, bl
  87         out    dx, al                                 ; enable channel
  88
  89         sti
  90         pop    esi
  91         pop    edx
  92         pop    eax
  93         ret