Problem from Axor #2

Hello, All! Here's another problem: There is a number HL, there is a certain part of this number DE, calculate the percentage in A of this part. We are waiting for your options for this procedure. Vega/ex-Style Group. FIDO: 2:5030/1512 ZXNET: 500:812/19 E-mail: vega56@mail.ru

Press RESET immediately, Vlad Sotnikov! On Sun, 14 Sep 03 23:14:17 +0400, Vlad Sotnikov wrote: VS> Here's another problem: VS> There is a number HL, there is a certain part of this number DE, calculate VS> percentage in A of this part. We are waiting for your options for this procedure. In other words, A = 100 * DE / HL. But the question arises about accuracy result and the acceptable range of numbers. Let's say that A is an integer, and HL and DE are unsigned 16-bit integers. Then the solution will have the following form (the percentage is rounded to nearest integer): push hl ld hl, 200 exx ldhl,0 push hl ld e, l ld d, h exx call lmul pop de call ldiv ld a, l srl a In this case, two library functions ldiv and lmul description of which and the text in assembly language is given below: lmul ===== (DE

Press RESET immediately, Kirill Frolov! On Mon, 15 Sep 2003 18:09:36 +0000 (UTC), Kirill Frolov wrote: KF> Then the solution will have the following form (the percentage is rounded to KF> nearest integer): KF> push hl KF> ld hl, 200 KF> exx KF> ld hl, 0 KF> push hl ^^^^^^^^^^^^^^^^^ This instruction should be deleted... KF> ld e, l KF> ld d, h KF> exx KF> call lmul KF> pop de KF> call ldiv KF> ld a, l KF> srl a

Press RESET immediately, Kirill Frolov! On Mon, 15 Sep 2003 18:22:37 +0000 (UTC), Kirill Frolov wrote: KF>> Then the solution will have the following form (the percentage is rounded to KF>> nearest integer): KF>> push hl KF>> ld hl, 200 KF>> exx KF>> ld hl, 0 KF>> push hl KF> ^^^^^^^^^^^^^^^^^ KF> this instruction should be deleted... KF>> ld e, l KF>> ld d, h KF>> exx KF>> call lmul KF>> pop de KF>> call ldiv KF>> ld a, l KF>> srl a Required condition -- DE <= HL, if I understood the condition correctly tasks. Actually, you can use the mul function to multiply 16-bit numbers, then the solution will look like this: push hl ld bc, 200 call mul push de exx pop hl ld de, 0 exx pop de call ldiv xor a ld a, l rra mul ==== (DE,HL) = DE * BC The function multiplies unsigned 16-bit numbers given inregisters DE and BC, and places the result in registers DE and HL. B The DE register stores the most significant bits of the result. Function runs in approximately 800 processor cycles. See also description of the amul function. EXPORT global mul ; long (DE,HL) = DE*BC ~730t. ; unsigned multiplication function for 16-bit numbers ; (C) Kirill Frolov ; idea by Vasil Ivanov ; dehl=de*bc ~730t. psect text mul: ldhl,0 ld a, c ld c, l ; 18 add a, a jr nc, $+4 add hl, de adc a, c ; 29 ; REPEAT 7 add hl, hl rla jr nc, $+4 add hl, de adc a, c ; 40*7 309 add hl, hl rla jr nc, $+4 add hl, de adc a,c add hl, hl rla jr nc, $+4 add hl, de adc a, c add hl, hl rla jr nc, $+4 add hl, de adc a,c add hl, hl rla jr nc, $+4 add hl, de adc a, c add hl, hl rla jr nc, $+4 add hl, de adc a,c add hl, hl rla jr nc, $+4 add hl, de adc a,c ; ENDR ld c, a push hl ; 0chl ld hl, 0 ld a, b ld b, l ; 33 add a, a jr nc, $+4 add hl, de add a, b ; 29 ; REPEAT 7 add hl, hl rla jr nc, $+4 add hl, de add a, b ; 40*7 309 add hl, hl rla jr nc, $+4 add hl, de add a, b add hl, hl rla jr nc, $+4 add hl, de add a, b add hl, hl rla jr nc, $+4 add hl, de add a, b add hl, hl rla jr nc, $+4 add hl, de add a, b add hl, hl rla jr nc, $+4 add hl, de add a, b add hl, hl rla jr nc, $+4 add hl, de add a, b ; ENDR ; ahl0 + 0cde = hlde pop de ld b, l ld l, h ld h, a ld a, d add a, b ld d, a ld b, 0 adc hl, bc ex de, hl ; 60 ret ; 729t.