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authorEddie Hung <eddie@fpgeh.com>2019-10-04 22:24:15 -0700
committerEddie Hung <eddie@fpgeh.com>2019-10-04 22:31:04 -0700
commit12fd2ec4f05ce5efda2a2d2e4d37aef013f2baf9 (patch)
tree8e8058f740e9e0233065ae41a6285e1ed537430a /passes
parent14e4aeece6adc0808ab1876f01752acb0833185a (diff)
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Improve comments for xilinx_dsp_CREG
Diffstat (limited to 'passes')
-rw-r--r--passes/pmgen/xilinx_dsp_CREG.pmg13
1 files changed, 7 insertions, 6 deletions
diff --git a/passes/pmgen/xilinx_dsp_CREG.pmg b/passes/pmgen/xilinx_dsp_CREG.pmg
index 3d911b478..3f8486406 100644
--- a/passes/pmgen/xilinx_dsp_CREG.pmg
+++ b/passes/pmgen/xilinx_dsp_CREG.pmg
@@ -7,11 +7,12 @@
// (attached to at most two $mux cells that implement clock-enable or
// reset functionality, using a subpattern discussed below)
// Notes:
-// - Separating out CREG packing is necessary since there is no guarantee
-// that the cell ordering corresponds to the "expected" case (i.e. the order
-// in which they appear in the source) thus the possiblity existed that a
-// register got packed as a CREG into a downstream DSP that should have
-// otherwise been a PREG of an upstream DSP that had not been visited yet
+// - Running CREG packing after xilinx_dsp_pack is necessary since there is no
+// guarantee that the cell ordering corresponds to the "expected" case (i.e.
+// the order in which they appear in the source) thus the possiblity existed
+// that a register got packed as a CREG into a downstream DSP that should
+// have otherwise been a PREG of an upstream DSP that had not been visited
+// yet
// - The reason this is separated out from the xilinx_dsp.pmg file is
// for efficiency --- each *.pmg file creates a class of the same basename,
// which when constructed, creates a custom database tailored to the
@@ -28,7 +29,7 @@ state <SigSpec> sigC sigP
state <bool> ffCcepol ffCrstpol
state <Cell*> ffC ffCcemux ffCrstmux
-// subpattern
+// Variables used for subpatterns
state <SigSpec> argQ argD
state <bool> ffcepol ffrstpol
state <int> ffoffset