Multiply 16 bits by 16 bits in software by http://elm-chan.org/
;-----------------------------------------------------------------------------: ; 16bit x 16bit unsigned multiply ; ; Register Variables ; Call: var1[1:0] = 16bit multiplicand ; var1[3:2] = <don't care> ; var2[1:0] = 16bit multiplier ; lc = <don't care> (high register must be allocated) ; ; Result:var1[3:0] = 32bit result of var1[1:0] * var2[1:0] ; var2[1:0] = <not changed> ; lc = 0 ; ; Size = 13 words ; Clock = 157..172 cycles (+ret) ; Stack = 0 byte mul16u: sub var13,var13 ;initialize variables sub var12,var12 ; ldi lc,17 ; lc = 17; brcc PC+3 ;---- calcurating loop add var12,var20 ; adc var13,var21 ; ror var13 ; ror var12 ; ror var11 ; ror var10 ; dec lc ;if (--lc > 0) brne PC-8 ; continue loop; ret mul16s: clr lc ; Optional fast signed helper clr var12 ; process with fast unsinged routine tst var11 brpl PC+6 inc var12 com var10 com var11 adc var10,lc adc var11,lc tst var21 brpl PC+6 inc var12 com var20 com var21 adc var20,lc adc var21,lc bst var12,0 rcall mul16u brtc PC+9 com var10 com var11 com var12 com var13 adc var10,lc adc var11,lc adc var12,lc adc var13,lc ret
| file: /Techref/atmel/avr/mul16x16sw-ec.htm, 1KB, , updated: 2007/9/14 17:13, local time: 2024/12/27 02:12,
3.147.82.22:LOG IN
|
| ©2024 These pages are served without commercial sponsorship. (No popup ads, etc...).Bandwidth abuse increases hosting cost forcing sponsorship or shutdown. This server aggressively defends against automated copying for any reason including offline viewing, duplication, etc... Please respect this requirement and DO NOT RIP THIS SITE. Questions? <A HREF="http://techref.massmind.org/techref/atmel/avr/mul16x16sw-ec.htm"> Atmel AVR, atmega, Microcontroller, embedded controller, math 16x16, elm-chan.org</A> |
| Did you find what you needed? |
Welcome to massmind.org! |
Welcome to techref.massmind.org! |
.