Verification of Parameterised FPGA Circuit Descriptions with Layout ...

CHAPTER 3. GENERATING PARAMETERISED LIBRARIES WITH LAYOUT 55
#define VERTICAL 0
#define HORIZONTAL 1
// Map combinator supporting horizontal and vertical placement
block map (int orientation) (int n, block R ‘a ∼ ‘b) (‘a i [n]) ∼ (‘b o[n])
attributes {
width = if(orientation==1, sum(k=0..n−1, width (i[k] ;R ;
o[k])), maxf(k=0..n−1, width (i[k] ;R ;o[k]))) .
height = if(orientation==1, maxf(k=0..n−1, height (i[k] ;R ;
o[k ])), sum(k=0..n−1, height (i[k] ;R ; o[k]))) .
} {
int j.
assert (orientation == 1 or orientation == 0) ”Invalid placement specified”;
for j = 0..n−1 {
if (orientation == 0) {
i [j] ; R ; o[j] at (0, sum(k=0..j−1,height(i[k] ;R ; o[k]))) .
} else {
i [j] ; R ; o[j] at (sum(k=0..j−1,width(i[k] ;R ;o[k ])), 0).
} .
} .
}
// Overloaded map block providing default placement interpretation
block map (int n, block R ‘a ∼ ‘b) (‘a i[n]) ∼ (‘b o[n]) → map VERTICAL.
Figure 3.15: Using overloading to provide multiple layout interpretations of combinators
be replaced with an enumerated type parameter with values of horizontal or vertical. In this
case the pre-processor definitions of the constants could be removed and the parameter-
checking assertion would not be necessary.
This approach can be applied for all combinator blocks which have more than one possible
orientation, for example a row could be laid out vertically or a column could be laid out
horizontally.
3.7 Compiling Placed Quartz Designs
Our goal when compiling Quartz is, where possible, to only partially evaluate the Quartz
description maintaining the maximum possible degree of parameterisation in the Pebble
output. When compiling Quartz with layout into Pebble relative positioning information
must be eliminated and replaced with expressions defining absolute coordinates.