wok annotate linld/stuff/src/MEMTOP.ASM @ rev 21791

Fix loram dos boot
author Pascal Bellard <pascal.bellard@slitaz.org>
date Thu Aug 01 15:16:29 2019 +0200 (2019-08-01)
parents 2373992ff751
children 6e3d30b3031f
rev   line source
pascal@19515 1 ;***************************************************************
pascal@19515 2 ;****** This file is distributed under GPL
pascal@19515 3 ;***************************************************************
pascal@19515 4 ideal
pascal@19515 5 %crefref
pascal@19515 6 %noincl
pascal@19515 7 %nomacs
pascal@19636 8 ifdef NO386
pascal@19636 9 p8086
pascal@19636 10 else
pascal@19515 11 p386
pascal@19636 12 endif
pascal@19515 13
pascal@20451 14 group DGROUP _TEXT,_BSS
pascal@19515 15 assume cs:DGROUP,ds:DGROUP
pascal@19515 16
pascal@19515 17
pascal@19515 18 segment _BSS byte public use16 'BSS'
pascal@19515 19
pascal@19515 20 saved15 dd ?
pascal@19515 21
pascal@19515 22 ends _BSS
pascal@19515 23
pascal@19515 24
pascal@19515 25 segment _TEXT byte public use16 'CODE'
pascal@19515 26
pascal@19515 27 ;***************************************************************
pascal@19515 28 ;u32 memtopz();
pascal@19515 29 ;***************************************************************
pascal@19515 30 proc _memtopz near
pascal@19515 31 ;***************************************************************
pascal@19515 32 ;u32 memtop_e801()
pascal@19515 33 ;***************************************************************
pascal@19515 34 ; proc _memtop_e801 near
pascal@19515 35
pascal@19515 36 xor cx,cx ;fix to work around buggy
pascal@19515 37 xor dx,dx ; BIOSes which dont clear/set
pascal@19515 38 stc ; carry on pass/error of
pascal@19515 39 mov ax,0E801h
pascal@19515 40 int 15h
pascal@19515 41 jc @@err
pascal@20453 42
pascal@20453 43 xchg ax,cx ;kludge to handle BIOSes
pascal@20453 44 jcxz @@use_cxdx ; which report their extended
pascal@20453 45 ; memory in AX/BX rather than
pascal@20453 46 ; CX/DX. The spec I have read
pascal@19515 47 @@use_axbx: mov dx,bx ; seems to indicate AX/BX
pascal@19882 48 xchg ax,cx ; are more reasonable anyway...
pascal@20453 49 @@use_cxdx: ;now: dx=64k units above 16m
pascal@20453 50 ; ax=1k units above 1m below 16m (max 3c00h)
pascal@20510 51 or dx,dx
pascal@19515 52 jz tokb ;dx=0 here, ax=kbs above 1m
pascal@19515 53 xor ax,ax ;ignore info on low 16M (assume full)
pascal@19515 54 ;add dx,100h ;account for low 16M
pascal@19515 55 inc dh ;account for low 16M (optimized)
pascal@19515 56 ret
pascal@19515 57 @@err:
pascal@19515 58 ; xor ax,ax
pascal@19515 59 ; cwd
pascal@19515 60 ; ret
pascal@19515 61 ; endp _memtop_e801
pascal@19515 62
pascal@19515 63
pascal@19515 64 ;***************************************************************
pascal@19515 65 ;u32 memtop_88()
pascal@19515 66 ;***************************************************************
pascal@19515 67 ; proc _memtop_88 near
pascal@19515 68
pascal@19515 69 mov ah,88h
pascal@19515 70 int 15h ;ax=kbs above 1m
pascal@20142 71 cmc ; error: cf=1 or ax=0
pascal@20142 72 sbb dx,dx
pascal@20142 73 and ax,dx ;
pascal@20142 74 jnz tokb ;happens on big mem systems
pascal@19879 75
pascal@19879 76 ;***************************************************************
pascal@19879 77 ;u32 memtop_cmos()
pascal@19879 78 ;***************************************************************
pascal@19879 79
pascal@19879 80 ;memtop_cmos:
pascal@19879 81 pushf
pascal@19879 82 call rdcmos17
pascal@19879 83 popf
pascal@19515 84 tokb:
pascal@21757 85 mov cl,10 ;multiply by 1024
pascal@21757 86 ifndef NO386
pascal@21757 87 add ah,4h ;account for 1024 low kb
pascal@21757 88 setc dl ; (optimized to death)
pascal@21757 89 shld dx,ax,cl
pascal@21757 90 shl ax,cl ; (kbytes -> bytes)
pascal@21791 91 ret
pascal@21757 92 else
pascal@19634 93 xor dx,dx
pascal@19515 94 add ah,4h ;account for 1024 low kb
pascal@19515 95 adc dx,dx ; (optimized to death)
pascal@21791 96 db 0A9h ; test ax,0C28Ch
pascal@21791 97 global N_LXLSH@ES:near
pascal@21791 98 N_LXLSH@ES:
pascal@21791 99 mov dx,es
pascal@20142 100 global N_LXLSH@:near
pascal@20142 101 N_LXLSH@:
pascal@19883 102 mov ch,0
pascal@19515 103 @@lp:
pascal@19883 104 shl ax,1
pascal@19515 105 rcl dx,1
pascal@19515 106 loop @@lp
pascal@21791 107 ret
pascal@21791 108 global N_LXLSH@4:near
pascal@21791 109 N_LXLSH@4:
pascal@21791 110 xor dx,dx
pascal@21791 111 mov cl,4
pascal@21791 112 jmp N_LXLSH@
pascal@19515 113 endif
pascal@19883 114
pascal@19515 115 ; endp _memtop_88
pascal@19515 116
pascal@19515 117 ; proc _memtopz near
pascal@19515 118
pascal@19515 119 ; call _memtop_e801
pascal@19515 120 ; jnz @@ok
pascal@19515 121 ; call _memtop_88
pascal@19515 122 ; jnz @@ok
pascal@19879 123 ; jmp memtop_cmos
pascal@19515 124
pascal@20142 125 rdcmos17: cli
pascal@20142 126 mov al,18h ; read bytes 17-18 from CMOS
pascal@19515 127 call @@rdcmos
pascal@19515 128 mov ah,al
pascal@19515 129 mov al,17h
pascal@19515 130 @@rdcmos: out 70h,al
pascal@19515 131 call @@ret
pascal@19515 132 in al,71h
pascal@19515 133 @@ret:
pascal@19515 134 ret
pascal@19515 135
pascal@19515 136
pascal@19515 137 ;***************************************************************
pascal@19515 138 ;u32 memtop();
pascal@19515 139 ;***************************************************************
pascal@19515 140 global _memtop:near
pascal@19515 141 _memtop:
pascal@19515 142 call _memtopz
pascal@19515 143 mov cx,40h ; min 4m
pascal@19515 144 ; If reported mem is ridiculously low, presume
pascal@19515 145 ; we had trouble detecting memory size
pascal@19515 146 cmp dx,cx
pascal@19515 147 jb @@set
pascal@20451 148 extrn _topmem:dword
pascal@20528 149 mov cx,[word _topmem+2]
pascal@20528 150 inc cx ; jcxnz
pascal@20528 151 loop @@topmemset
pascal@20528 152 mov ch,10h ; default = max 256m
pascal@20528 153 @@topmemset:
pascal@19515 154 ; Kernel can have trouble with initrd at very high addr:
pascal@19515 155 ; limit mem top to 256m
pascal@19515 156 cmp dh,ch
pascal@19515 157 jb @@done
pascal@19515 158 @@set:
pascal@19515 159 xchg ax,cx
pascal@19515 160 cwd
pascal@19515 161 xchg ax,dx
pascal@19515 162 @@done:
pascal@19515 163 ; Round down to page boundary.
pascal@19515 164 ; Or else initrd's tail may end up in last, partial page.
pascal@19515 165 ; Kernel will refuse to use such initrd.
pascal@19515 166 and ax,0f000h
pascal@19515 167 ;@@ok:
pascal@19515 168 ret
pascal@19515 169
pascal@19515 170 endp _memtopz
pascal@19515 171
pascal@19515 172 ;***************************************************************
pascal@19515 173 ;void hook_int15_88();
pascal@19515 174 ;***************************************************************
pascal@19515 175 global _hook_int15_88:near
pascal@19515 176 proc _hook_int15_88 near
pascal@19515 177
pascal@19515 178 ifndef xmm_hook
pascal@19515 179 mov ax,4300h
pascal@19515 180 int 2fh
pascal@19571 181 cmp al,80h ; 80h = XMS driver installed
pascal@19515 182 je @@skip
pascal@19515 183 endif
pascal@19883 184 xor bx,bx
pascal@19883 185 mov es,bx
pascal@19571 186 ifndef NO386
pascal@19876 187 push cs
pascal@19876 188 push offset int15_88
pascal@19876 189 pop eax
pascal@19883 190 xchg eax,[es:bx+15*4]
pascal@19515 191 mov [saved15],eax
pascal@19515 192 else
pascal@19876 193 mov ax,offset int15_88
pascal@19883 194 xchg ax,[es:bx+15*4]
pascal@19515 195 mov [word saved15],ax
pascal@19876 196 mov ax,cs
pascal@19883 197 xchg ax,[es:bx+15*4+2]
pascal@19515 198 mov [word saved15+2],ax
pascal@19515 199 endif
pascal@21757 200 ;push ds
pascal@21757 201 ;pop es
pascal@19515 202 @@skip:
pascal@19515 203 ret
pascal@19515 204 int15_88:
pascal@19515 205 cmp ah,88h
pascal@19515 206 je @@do88
pascal@19515 207 jmp [saved15]
pascal@19515 208 @@do88:
pascal@19515 209 pushf
pascal@21302 210 call [saved15]
pascal@20510 211 or ax,ax
pascal@19515 212 jnz @@iret
pascal@19515 213
pascal@19515 214 ;****** Read extended mem size (CMOS bytes 17h,18h (lo,hi))
pascal@19515 215 call rdcmos17
pascal@19515 216 @@iret:
pascal@19515 217 iret
pascal@19515 218
pascal@19515 219 endp _hook_int15_88
pascal@19515 220
pascal@19515 221 ends _TEXT
pascal@19515 222
pascal@19515 223 end
pascal@19515 224
pascal@19515 225 ;###### END OF FILE ############################################