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Length: 1792 (0x700)
Types: TextFile
Names: »MPASR.MAC«
└─⟦01b5c9619⟧ Bits:30005906 Microsoft Multiplan v1.05 og HELP
└─ ⟦this⟧ »MPASR.MAC«
; ; ; Title Multiple-Precision Arithmetic Shift Right ; Name: MPASR ; ; ; Purpose: Arithmetic shift right a multi-byte operand ; N bits ; ; Entry: Register pair HL = base address of operand ; Register B = lenght of operand in bytes ; 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 with the most significant ; bit propagated. ; CARRY := last bit shifted from least ; significant position. ; ; Registers used: AF,BC,DE,HL ; ; Time: 59 cycles overhead plus ; ((34 * lenght) + 46) cycles per shift ; ; Size: Program 28 bytes ; ; ; MPASR: ;Exit if number of shifts or lenght of operand is 0 ;or clears carry in eigher 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 ;HL = address of msb ;C = number of shifts ;A = lenght of operand ;Loop on number of shifts to preform ;initial carry = most significant bit of entire operand loop: ld b,(hl) ;Get most significant byte rl b ;Carry = most significant bit ld b,a ld e,l ;Save address of msb ld d,h ;Rotate bytes right starting with most significant asrlp: rr (hl) ;Rotata a byte right dec hl ;Decrement to less significant byte djnz asrlp cont: ld l,e ;Restore address of msb ld h,d dec c ;Decrement number of shifts jr nz,loop ret «eof»