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File List | 1983-11-17 | 15.2 KB | 302 lines

The Microsoft MACRO Assembler 11-17-83 PAGE 1-1 'FREE --- report free space on disk' 1 name free 2 page 60,132 3 title 'FREE --- report free space on disk' 4 5 ;FREE --- a utility to report free space on 6 ; the default or selected disk drive. 7 ; 8 ;Requires PC-DOS or MS-DOS 2.0 9 ; 10 ;Used in the form: 11 ;A>FREE [unit:] 12 ;(item in square brackets is optional) 13 ; 14 ;version 1.0 July 1, 1984 15 ;Copyright (c) 1984 by Ray Duncan 16 ;May be freely reproduced for non-commercial use. 17 18 = 000D cr equ 0dh ;ASCII carriage return 19 = 000A lf equ 0ah ;ASCII line feed 20 = 0020 blank equ 20h ;ASCII space code 21 = 0024 eom equ '$' ;end of string marker 22 23 24 ;Here we define a dummy segment containing lavbels 25 ;for thedefault fiel control black and the command tail buffer, 26 ;so that the main program can access those locations. 27 ; 28 0000 psp segment para public 'PSP' 29 30 005C org 05ch 31 005C fcb label byte ;default file control block 32 33 0080 org 080h 34 0080 command label byte ;default command buffer 35 36 0080 psp ends 37 38 0000 cseg segment para public'CODE' 39 40 assume cs:cseg,ds:psp,es:data,ss:stack 41 42 0000 get_drive proc near ;get drive selection, if any, 43 ;otherwise obtain the identity 44 ;of the current disk drive. 45 ;Return drive (1=A,2=B,etc)in RL. 46 ; 47 0000 A0 005C R mov al,fcb ;Pick up the drive code, parsed 48 ;by DOS into the default file 49 ;control block. 50 0003 0A C0 or al,al ;Is it the default? 51 0005 75 06 jnz get_drive1 ;no, use it 52 0007 B4 19 mov ah,19h ;Yes, get the actual current 53 0009 CD 21 int 21h ;drive from PC-DOS. 54 000B FE C0 inc al ;Increment to match FCB code. 55 000D get_drive1: ;Return drive code in RL. The Microsoft MACRO Assembler 11-17-83 PAGE 1-2 'FREE --- report free space on disk' 56 000D C3 ret 57 000E get_drive endp 58 59 000E free proc far ;entry point from PC-DOS 60 000E 1E push ds ;Save OS:0000 for final 61 000F 33 C0 xor ax,ax ;return to PC-DOS 62 0011 50 push ax 63 0012 B8 ---- R mov ax,data ;make our data segment 64 0015 8E C0 mov es,ax ;addressable via ES register. 65 0017 B4 30 mov ah,30h ;check version of PC-DOS. 66 0019 CD 21 int 21h 67 001B 3C 02 cmp al,2 68 001D 73 0A jae free1 ;proceed, DOS 2.0 or greater. 69 001F BA 0048 R mov dx,offset msg2 ;DOS 1.x -- print error message 70 0022 8C C0 mov ax,es ;and exit. First fix up DS register 71 0024 8E D8 mov ds,ax ;;so error message is addressable. 72 0026 EB 01 90 jmp free1 73 74 0029 E8 0000 R free1: call get_drive ;get drive selection into DL. 75 002C 06 push es ;copy ES to Ds for remainder 76 002D 1F pop ds ;of the program... 77 assume ds:data ;and tell assembler about it. 78 002E 8A D0 mov dl,al 79 0030 04 40 add al,'A'-1 ;form drive letter from drive soce, 80 0032 A2 001F R mov outputb,al ;and put i into the ouput string. 81 0035 B4 36 mov ah,36h ;nob call dos to get free disk space 82 0037 CD 21 int 21h 83 0039 3D FFFF cmp ax,-1 ;was drive invalid? 84 003C 74 13 je free3 ;yes, go print error message 85 ;drive was ok, so now registers are. 86 87 ;RX=number of sectors per cluser 88 ;BX=available clusters, 89 ;CX=number of bytes per sector, 90 ;DX=total clusters per drive. 91 ;calculate free space: 92 003E F7 E1 mul cx ;sectors per cluster * bytes/sector 93 ;(we assume no overflow into DX 94 0040 F7 E3 mul bx ;then* available clusers 95 0042 BE 000B R mov si,offset (outputa+9) 96 0045 B9 000A mov cx,10 ;CX = 10, radix for conversion 97 0048 E8 0059 R call bin_to_asc ;convert free space value to ASCII, 98 004B BA 0000 R mov dx,offset output 99 004E EB 04 90 jmp free4 ;and print it out. 100 101 0051 BA 0024 R free3: mov dx,offset msg1 ;illegal drive, print error 102 103 0054 B4 09 free4: mov ah,9 ;prin the string whose address 104 0056 CD 21 int 21h ;is in DX. 105 0058 CB ret ;then return to DOS. 106 107 0059 free endp 108 109 ;Convert 32 bit binary value to ASCII string. 110 ; The Microsoft MACRO Assembler 11-17-83 PAGE 1-3 'FREE --- report free space on disk' 111 ;Call with DX:AX = signed 32 but value 112 ; CX = radix 113 ; SI = last byte of area to store resulting string 114 ; (make sure enough room is available to store 115 ; the string in the radix you have selected.) 116 ; 117 ;Destroys RX,BX,CX,DX, and SI. 118 ; 119 0059 bin_to_asc proc near ;convert DX:AX to ASCII. 120 ;force storage of at least 1 digit. 121 0059 C6 04 30 mov byte ptr [si],'0' 122 005C 0B D2 or dx,dx ;test sign of 32 bit value, 123 005E 9C pushf ;and save sign on stack. 124 005F 79 0A jns bin1 ;jump if it was positive. 125 0061 F7 D2 not dx ;it was negative, take 2's complemen 126 127 0063 F7 D0 not ax ;of the value. 128 0065 05 0001 add ax,1 129 0068 83 D2 00 adc dx,0 130 006B bin1: ;divide the 32 bit balue by the radi 131 132 ;to extract the next digit for the 133 ;forming string. 134 006B 8B D8 mov bx,ax ;is the value zero yet? 135 006D 0B DA or bx,dx 136 006F 74 13 jz bin3 ;yes, we are done converting. 137 0071 E8 008B R call divide ;no, divide by radix. 138 0074 80 C3 30 add bl,'0' ;convert the remainder to an ASCII 139 0077 80 FB 39 cmp bl,'9' ;we might be converting to hex ASCII 140 141 007A 7E 03 jle bin2 ;jump if in range 0-9, 142 007C 80 C3 07 add bl,'A'-'9'-1 ;correct it if in range A-F. 143 007F 88 1C bin2: mov [si],bl ;store this character into string. 144 ;to extract the next digit for the 145 ;forming string. 146 0081 4E dec si ;back up throught string, 147 0082 EB E7 jmp bin1 ;and so it again. 148 0084 bin3: ;restore sign flag, 149 0084 9D popf ;was original value negative? 150 0085 79 03 jns bin4 ;no, jump 151 ;yes, store sign into ouput string. 152 0087 C6 04 2D mov byte ptr[si],'-' 153 008A C3 bin4: ret ;back to caller. 154 008B bin_to_asc endp 155 156 157 ;General purpose 32 bit by 16 bit unsigned divide. 158 ;This must be used instead of the plain machine unsigned divide 159 ;for cases where the quotient may overflow 16 bits (for example, 160 ;dividing 100,000 by 2). If called with a zero divisor, this 161 ;routine returns the dividend unchanged and gives no warning. 162 ; 163 ;Call with DX:AX = 32 bit dividend 164 ; CX = divisor 165 ; The Microsoft MACRO Assembler 11-17-83 PAGE 1-4 'FREE --- report free space on disk' 166 ;Returns DX:AX = quotient 167 ; BX = remainder 168 ; CX = divisor (unchanged) 169 ; 170 171 008B divide proc near ;Divide DX:AX by CX 172 008B E3 0E jcxz div1 ;exit if divide by zero 173 008D 50 push ax ;0:dividend_upper/divisor 174 008E 8B C2 mov ax,dx 175 0090 33 D2 xor dx,dx 176 0092 F7 F1 div cx 177 0094 8B D8 mov bx,ax ;BX = quotient1 178 0096 58 pop ax ;remainder1:dividend_lower.divisor 179 0097 F7 F1 div cx 180 0099 87 DA xchg bx,dx ;DX:RX = quotient1:quotient2 181 009B C3 div1: ret ;BX = remainder2 182 009C divide endp 183 009C cseg ends 184 185 186 0000 data segment para public 'DATA' 187 188 0000 0D 0A output db cr,lf 189 0002 0A [ outputa db 10 dup(blank) 190 20 191 ] 192 193 194 195 000C 62 79 74 65 73 20 db 'bytes free on drive' 196 66 72 65 65 20 6F 197 6E 20 64 72 69 76 198 65 199 200 201 001F 78 3A 0D 0A 24 outputb db 'x:',cr,lf,eom 202 203 0024 0D 0A msg1 db cr,lf 204 0026 54 68 61 74 20 64 db 'That disk drive does not exist.' 205 69 73 6B 20 64 72 206 69 76 65 20 64 6F 207 65 73 20 6E 6F 74 208 20 65 78 69 73 74 209 2E 210 211 212 0045 0D 0A 24 db cr,lf,eom 213 214 0048 0D 0A msg2 db cr,lf 215 004A 52 65 71 75 69 72 db 'Requires DOS version 2 or greater.' 216 65 73 20 44 4F 53 217 20 76 65 72 73 69 218 6F 6E 20 32 20 6F 219 72 20 67 72 65 61 220 74 65 72 2E The Microsoft MACRO Assembler 11-17-83 PAGE 1-5 'FREE --- report free space on disk' 221 222 223 224 006C 0D 0A 24 db cr,lf,eom 225 006F data ends 226 227 0000 stack segment para stack 'STACK' 228 0000 40 [ db 64 dup (?) 229 ?? 230 ] 231 232 233 0040 stack ends 234 235 end free The Microsoft MACRO Assembler 11-17-83 PAGE Symbols-1 'FREE --- report free space on disk' Segments and groups: N a m e Size align combine class CSEG . . . . . . . . . . . . . . 009C PARA PUBLIC 'CODE' DATA . . . . . . . . . . . . . . 006F PARA PUBLIC 'DATA' PSP. . . . . . . . . . . . . . . 0080 PARA PUBLIC 'PSP' STACK. . . . . . . . . . . . . . 0040 PARA STACK 'STACK' Symbols: N a m e Type Value Attr BIN1 . . . . . . . . . . . . . . L NEAR 006B CSEG BIN2 . . . . . . . . . . . . . . L NEAR 007F CSEG BIN3 . . . . . . . . . . . . . . L NEAR 0084 CSEG BIN4 . . . . . . . . . . . . . . L NEAR 008A CSEG BIN_TO_ASC . . . . . . . . . . . N PROC 0059 CSEG Length =0032 BLANK. . . . . . . . . . . . . . Number 0020 COMMAND. . . . . . . . . . . . . L BYTE 0080 PSP CR . . . . . . . . . . . . . . . Number 000D DIV1 . . . . . . . . . . . . . . L NEAR 009B CSEG DIVIDE . . . . . . . . . . . . . N PROC 008B CSEG Length =0011 EOM. . . . . . . . . . . . . . . Number 0024 FCB. . . . . . . . . . . . . . . L BYTE 005C PSP FREE . . . . . . . . . . . . . . F PROC 000E CSEG Length =004B FREE1. . . . . . . . . . . . . . L NEAR 0029 CSEG FREE3. . . . . . . . . . . . . . L NEAR 0051 CSEG FREE4. . . . . . . . . . . . . . L NEAR 0054 CSEG GET_DRIVE. . . . . . . . . . . . N PROC 0000 CSEG Length =000E GET_DRIVE1 . . . . . . . . . . . L NEAR 000D CSEG LF . . . . . . . . . . . . . . . Number 000A MSG1 . . . . . . . . . . . . . . L BYTE 0024 DATA MSG2 . . . . . . . . . . . . . . L BYTE 0048 DATA OUTPUT . . . . . . . . . . . . . L BYTE 0000 DATA OUTPUTA. . . . . . . . . . . . . L BYTE 0002 DATA Length =000A OUTPUTB. . . . . . . . . . . . . L BYTE 001F DATA Warning Severe Errors Errors 0 0