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Length: 1664 (0x680)
Types: TextFile
Names: »MPLSR.MAC«
└─⟦01b5c9619⟧ Bits:30005906 Microsoft Multiplan v1.05 og HELP
└─ ⟦this⟧ »MPLSR.MAC«
; ; ; Title Multiple-Precision Logical Shift Right ; Name: MPLSR ; ; ; Purpose: Logical shift right a multi-byte operand ; N bits ; ; Entry: Register pair HL = Base address of operand ; Register B = lenght of operand ; Register C = Number of bits to shift ; ; The operand is stored with ARRAYÆ0Å as its ; least significant byte and ARRAYÆLENGHT-1Å ; its most significant byte, where ARRAY ; is its base address. ; ; Exit: Operand shifted right filling the most ; significant bits with zeros ; CARRY := Last bit shifted from ; leasr significant position ; ; Registers used: AF,BC,DE,HL ; ; Time: 59 cycles overhead plus ; ((34 * lenght) + 35) cycles per shift ; ; Size: Program 26 bytes ; ; ; MPLSL: ;Exit if number of shifts or lenght of operand is 0 ;or clears carry in eighter case ld a,c or a ret z ;Return if number of shifts is 0 ld a,b or a ret z ;Return if lenght of operand is 0 ;Calculate address of most significant (last) byte ld e,b ;Address of MSB = base + Lenght - 1 ld d,0 add hl,de dec hl ;Loop on number of shifts to perform ;A = lenght of operand ;C = number of shifts ;HL = address of MSB ;Carry = 0 initialy for logical shift loop: ld e,l ;Save address of MSB ld d,h ld b,a ;B = lenght of operand or a ;Clear carry for logical shift ;Rotate bytes starting with most significant lsllp: rr (hl) ;Rotate next byte right dec hl ;Decrement to less significant byte djnz lsllp ld l,e ;Restore address of MSB ld h,d dec c ;Decrement number of shifts jr nz,loop ret «eof»