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| comp.lang.asm.x86 | Ahh, the lost art of x86 assembly | 4,675 messages |
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| Message 3,332 of 4,675 |
| wolfgang kern to All |
| Re: Hex 2 Bin (1/2) |
| 05 Apr 18 12:04:21 |
From: nowhere@never.at Kerr-Mudd,John posted: after all I see some neat tricks in your code ... > minicalc.com > ->u100 l100 > 161D:0100 BE 80 00 mov si,0080 > 161D:0103 AC lodsb > 161D:0104 98 cbw > 161D:0105 91 xchg ax,cx > 161D:0106 E8 8F 00 call 0198 ; getnum > 161D:0109 72 4C jb 0157 > 161D:010B 95 xchg ax,bp I'm not sure where the call returns to if only spaces or cx=0. > 161D:010C 4E dec si > 161D:010D AC lodsb > 161D:010E 3C 20 cmp al,20 > 161D:0110 E1 FB loopzw 010D > 161D:0112 74 43 jz 0157 > 161D:0114 50 push ax ; save operator > 161D:0115 E8 80 00 call 0198 ; getnum > 161D:0118 92 xchg ax,dx > 161D:0119 58 pop ax > 161D:011A 72 3B jb 0157 > testop: > 161D:011C 98 cbw > 161D:011D 2C 25 sub al,25 why sub 25 ? Ok I see, it makes ax=0 -> bp=0 + clear dx before DIV and now I see how you assigned the "%" to MOD > 161D:011F 74 3B jz 015C > 161D:0121 3C 06 cmp al,06 > 161D:0123 74 12 jz 0137 > 161D:0125 3C 08 cmp al,08 > 161D:0127 74 13 jz 013C > 161D:0129 3C 05 cmp al,05 > 161D:012B 74 14 jz 0141 > 161D:012D 3C 0A cmp al,0A > 161D:012F 74 2B jz 015C > 161D:0131 3C FE cmp al,FE > 161D:0133 74 11 jz 0146 > 161D:0135 EB 20 jmp 0157 dual branch ? jnz and reorder can make one or two branches vanish > addnums: > 161D:0137 95 xchg ax,bp > 161D:0138 01 D0 add ax,dx > 161D:013A EB 2D jmp 0169 > subnums: > 161D:013C 95 xchg ax,bp > 161D:013D 29 D0 sub ax,dx > 161D:013F EB 28 jmp 0169 ADD and SUB could be combined subnum: NEG ax addnum: xchg .. ADD .. > mulnums: > 161D:0141 95 xchg ax,bp > 161D:0142 F7 E2 mul dx > 161D:0144 EB 23 jmp 0169 > expnums: > 161D:0146 89 E8 mov ax,bp > 161D:0148 51 push cx > 161D:0149 89 D1 mov cx,dx > 161D:014B 49 dec cx > 161D:014C F7 E5 mul bp > 161D:014E 09 D2 or dx,dx > 161D:0150 75 05 jnz 0157 > 161D:0152 E2 F8 loopw 014C > 161D:0154 59 pop cx > 161D:0155 EB 12 jmp 0169 > prtusage: > 161D:0157 BA D2 01 mov dx,01D2 > 161D:015A EB 37 jmp 0193 > divmodnums: > 161D:015C 53 push bx > 161D:015D 89 D3 mov bx,dx > 161D:015F 99 cwd > 161D:0160 95 xchg ax,bp > 161D:0161 F7 F3 div bx > 161D:0163 5B pop bx > 161D:0164 45 inc bp > 161D:0165 4D dec bp > 161D:0166 75 01 jnz 0169 ; if mod prt dx > 161D:0168 92 xchg ax,dx > prtnum: > 161D:0169 BF FB 01 mov di,01FB > 161D:016C B1 68 mov cl,68 > 161D:016E 80 FB 10 cmp bl,10 > 161D:0171 74 0A jz 017D > 161D:0173 B1 2B mov cl,2B > 161D:0175 09 C0 or ax,ax > 161D:0177 79 04 jns 017D > 161D:0179 F7 D8 neg ax > 161D:017B B1 2D mov cl,2D > 161D:017D 31 D2 xor dx,dx > 161D:017F F7 F3 div bx > 161D:0181 92 xchg ax,dx > 161D:0182 3C 0A cmp al,0A > 161D:0184 1C 69 sbb al,69 > 161D:0186 2F das > 161D:0187 88 05 mov [di],al > 161D:0189 4F dec di > 161D:018A 92 xchg ax,dx > 161D:018B 09 C0 or ax,ax > 161D:018D 75 EE jnz 017D > 161D:018F 88 0D mov [di],cl > 161D:0191 57 push di > 161D:0192 5A pop dx > 161D:0193 B4 09 mov ah,09 > 161D:0195 CD 21 int 21 > 161D:0197 C3 ret > > getnum: > 161D:0198 AC lodsb > 161D:0199 3C 20 cmp al,20 > 161D:019B E1 FB loopzw 0198 > 161D:019D 74 30 jz 01CF ?? if first call: 01CF pops ax,dx,pb,ip ?? (JZ 01CE) > 161D:019F BB 0A 00 mov bx,000A ; assume decimal > 161D:01A2 3C 68 cmp al,68 ; 'h' > 161D:01A4 75 03 jnz 01A9 > 161D:01A6 B3 10 mov bl,10 ; is hex > 161D:01A8 AC lodsb > 161D:01A9 55 push bp > 161D:01AA 52 push dx > 161D:01AB 3C 2D cmp al,2D ; -ve? > 161D:01AD 9C pushfw > 161D:01AE 74 01 jz 01B1 > 161D:01B0 4E dec si ;not minus, go back a char > 161D:01B1 31 ED xor bp,bp > 161D:01B3 AC lodsb > 161D:01B4 3C 30 cmp al,30 > 161D:01B6 72 0E jb 01C6 ; end on <0 > 161D:01B8 24 4F and al,4F ; hex2bin > 161D:01BA D4 37 aam 37 > 161D:01BC 98 cbw > 161D:01BD 95 xchg ax,bp > 161D:01BE F7 E3 mul bx > 161D:01C0 72 0D jb 01CF > 161D:01C2 01 C5 add bp,ax ; accumulate num in bp > 161D:01C4 E2 ED loopw 01B3 > 161D:01C6 95 xchg ax,bp > 161D:01C7 9D popfw > 161D:01C8 75 02 jnz 01CC > 161D:01CA F7 D8 neg ax ; if -ve > 161D:01CC 5A pop dx > 161D:01CD 5D pop bp > 161D:01CE C3 ret > errnum: > 161D:01CF 58 pop ax ;drop saved flags, cy still set > 161D:01D0 EB FA jmp 01CC > db 'Usage is: calc num1 [+-*/%#] num2',cr,lf,'$' > db '-$$$$$$' you use the "h" as prefix while I (optionally) display it after Num. __ wolfgang --- SoupGate-Win32 v1.05 * Origin: you cannot sedate... all the things you hate (1:229/2) |
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