MAC-unit Syntax for CF V1

wadehassler — Thu, 29 Oct 2020 09:49:30 GMT

The Coldire V1's multiplier/accumulator is described as having a multiply/accumulate/load mode to speed up MAC-operations.

It also can implement circular addressing, so that no overhead is incurred for address-checking.

I can't figure out the syntax, however: it seems that one must write:

mac.w  D0.L, D1.L, (A0)+&  ,  D0 ;

... in order to

word-multiply D0 and D1,

add their product to the accumulator,

increment A0,

'and' A0's address with the MASK-register,

load the value newly-indicated by A0 into D0

But I cannot have both the '-' and '&' in the line at the same time. This seems odd, as if A0 must be separately incremented OR it must be separately masked.

What have I missed?

Wade Hassler

Re: MAC-unit Syntax for CF V1

kef — Thu, 06 Sep 2012 17:39:01 GMT

But I cannot have both the '-' and '&' in the line at the same time.

As I understand it, you can:

mac.w D0.L, D1.L, -(A0)& , D0

If you look at other CF instructions and addressing modes available, postincrement (Ax)+ and predecrement -(Ax) are available, but not +(Ax) or (Ax)-.

D0 in your list of steps should be loaded with data at (A0 & mask) frist, and only then A0 should be incremented to point to the next data. In -(Ax) case, A0 is first decremented, and then D0 is loaded.

topic MAC-unit Syntax for CF V1 in CodeWarrior for MCU

MAC-unit Syntax for CF V1

Re: MAC-unit Syntax for CF V1