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Notes

The following is a place to put notes on work being done, issues found, solutions being worked on etc.

Magic

Issues with FIXED_BBOX

TL;DR - ‘snap int’ is required to ensure that FIXED_BBOX values are handled properly.

Issues has been experienced with Magic when trying to set the FIXED_BBOX parameter on a cell, and the origin.

The aim was to set these parameters so that cells could be easily used to store font characters/glyphs with their widths, with the origin on the baseline of the character. It wasn’t obvious how to do this correctly.

The process that was found to work:

load <cell>
snap grid
-- position box at origin --
snap int
box position
move origin <x> <y>

snap grid
-- position box for BBOX --
snap int
box position
box size
property FIXED_BBOX "<x1> <y1> <x2=x1+width> <y2=y1+height>"
save

Note 1: While the box parameters are given as x, y, width and height, the FIXED_BBOX parameters are given as corner coordinates - x1,y1,x2,y2.

Note 2: When using FIXED_BBOX, need to use the commant ‘snap int’ (snap internal) so that coordinates are handled correctly. ‘snap grid’ is still used to position the box correctly.

A little more precisely:

load <cell>
snap grid
-- position box at origin --
snap int
move origin [lindex [box pos] 0] [lindex [box pos] 1]
# Check origin has been moved correctly.
box pos 0 0
property FIXED_BBOX "0 -60 120 210"
save

Issue: The ‘move origin’ command does not change the coordinate of the box, which will move when this command is run.

The cells are saved with the ‘FIXED_BBOX’ parameter, but it appears to be a bit of a hack, as it is required to be set as a string (with quotes) but is actually an array. This has been hacked in specifically for the ‘FIXED_BBOX’ parameter and also requires that the ‘CDFIXEDBBOX’ flag is set on the cell. (This flag is referred to as CD_FIXEDBBOX in the commit logs.)

Magic Code

FIXED_BBOX appears in the code in the following locations

./database/DBcellsrch.c:1923:	propval = (char *)DBPropGet(cellDef, "FIXED_BBOX", &found);
./database/DBcellsrch.c:1935:		DBPropPut(cellDef, "FIXED_BBOX", propval);
./database/DBcellsrch.c:2132:	propval = (char *)DBPropGet(cellDef, "FIXED_BBOX", &found);
./database/DBcellsrch.c:2144:		DBPropPut(cellDef, "FIXED_BBOX", propval);
./database/DBprop.c:70:    /* Special handling of FIXED_BBOX, which uses CDFIXEDBBOX as a quick lookup */
./database/DBprop.c:71:    if (!strcmp(name, "FIXED_BBOX"))
./database/DBprop.c:218:    /* Since CDFIXEDBBOX requires a FIXED_BBOX property, clearing all	*/
./database/DBio.c:1615:	    /* Also process FIXED_BBOX property, as units must match */
./database/DBio.c:1617:	    if (!strcmp(propertyname, "FIXED_BBOX"))
./database/DBio.c:2603:    /* NOTE:  FIXED_BBOX is treated specially;  values are database */
./database/DBio.c:2607:    propvalue = (char *)DBPropGet(cellDef, "FIXED_BBOX", &propfound);
./database/DBio.c:2626:	    DBPropPut(cellDef, "FIXED_BBOX", propscaled);
./database/DBio.c:2637:    if (propfound) DBPropPut(cellDef, "FIXED_BBOX", propvalue);
./select/selDisplay.c:322:	propval = (char *)DBPropGet(scx->scx_use->cu_def, "FIXED_BBOX", &found);
./lef/defRead.c:851:	/* Abstract views with fixed bounding boxes use the FIXED_BBOX property */
./lef/defRead.c:858:	    propval = DBPropGet(use->cu_def, "FIXED_BBOX", &found);
./lef/lefWrite.c:342:		propvalue = (char *)DBPropGet(def, "FIXED_BBOX", &propfound);
./lef/lefWrite.c:1248:    /* If a bounding box has been declared with the FIXED_BBOX property	*/
./lef/lefWrite.c:1256:	propvalue = (char *)DBPropGet(def, "FIXED_BBOX", &found);
./lef/lefRead.c:1925:	/* Define the FIXED_BBOX property to match the LEF macro */
./lef/lefRead.c:1934:	    DBPropPut(lefMacro, "FIXED_BBOX", propval);
./lef/lefRead.c:1948:	    DBPropPut(lefMacro, "FIXED_BBOX", propval);
./lef/lefRead.c:1963:	    DBPropPut(lefMacro, "FIXED_BBOX", propval);
./cif/CIFgen.c:4141:		    propvalue = (char *)DBPropGet(origDef, "FIXED_BBOX", &found);
./cif/CIFrdcl.c:700:    /* layer, then the last one defines the FIXED_BBOX property.    */
./cif/CIFrdcl.c:739:	propvalue = (char *)DBPropGet(cifReadCellDef, "FIXED_BBOX", &found);
./cif/CIFrdcl.c:765:    DBPropPut(cifReadCellDef, "FIXED_BBOX", storedvalue);
./cif/CIFint.h:133: * CIFOP_BOUNDARY -	Added 6/5/19---map the FIXED_BBOX property bounding
./commands/CmdCD.c:3848:     * set, then used the property FIXED_BBOX to set the bounding box.
./commands/CmdCD.c:3856:	propvalue = (char *)DBPropGet(def, "FIXED_BBOX", &found);

CDFIXEDBBOX appears in the following locations

./database/DBcellsrch.c:1917:    if ((cellDef->cd_flags & CDFIXEDBBOX) != 0)
./database/DBcellsrch.c:2126:    if ((cellDef->cd_flags & CDFIXEDBBOX) != 0)
./database/DBprop.c:70:    /* Special handling of FIXED_BBOX, which uses CDFIXEDBBOX as a quick lookup */
./database/DBprop.c:74:	    cellDef->cd_flags &= ~CDFIXEDBBOX;
./database/DBprop.c:76:	    cellDef->cd_flags |= CDFIXEDBBOX;
./database/DBprop.c:218:    /* Since CDFIXEDBBOX requires a FIXED_BBOX property, clearing all	*/
./database/DBprop.c:220:    cellDef->cd_flags &= ~CDFIXEDBBOX;
./database/database.h:383: *	CDFIXEDBBOX means that this cell has been declared to be a
./database/database.h:416:#define CDFIXEDBBOX	 0x0080
./database/database.h.in:383: *	CDFIXEDBBOX means that this cell has been declared to be a
./database/database.h.in:416:#define CDFIXEDBBOX	 0x0080
./database/DBio.c:1648:		    cellDef->cd_flags |= CDFIXEDBBOX;
./select/selDisplay.c:317:    if (scx->scx_use->cu_def->cd_flags & CDFIXEDBBOX)
./lef/defRead.c:853:	if (use->cu_def->cd_flags & CDFIXEDBBOX)
./lef/lefWrite.c:340:	    if (siteDef->cd_flags & CDFIXEDBBOX)
./lef/lefWrite.c:1251:    if (def->cd_flags & CDFIXEDBBOX)
./lef/lefRead.c:1929:	    lefMacro->cd_flags |= CDFIXEDBBOX;
./lef/lefRead.c:1943:	    lefMacro->cd_flags |= CDFIXEDBBOX;
./lef/lefRead.c:1956:	    lefMacro->cd_flags |= CDFIXEDBBOX;
./cif/CIFgen.c:4136:		if (origDef && (origDef->cd_flags & CDFIXEDBBOX))
./cif/CIFrdcl.c:731:    if (cifReadCellDef->cd_flags & CDFIXEDBBOX)
./cif/CIFrdcl.c:766:    cifReadCellDef->cd_flags |= CDFIXEDBBOX;
./commands/CmdCD.c:3847:     * Get def's bounding box.  If def is an abstract view with CDFIXEDBBOX
./commands/CmdCD.c:3851:    if (def->cd_flags & CDFIXEDBBOX)

Error with magic tcl script - Box tool must be present

To make sure that the box tool is available when running an tcl script, use:

Running Magic non-interactively

In the ‘caravel’ projects there are a couple useful examples in ‘scripts’.

‘core-scripts/magic-drc.sh’ calls magic via:

magic \
    -noconsole \
    -dnull \
    -rcfile $MAGIC_MAGICRC \
    $TCL_CALL_PATH/magic-drc.tcl \
    </dev/null \
    |& tee $OUT_DIR/magic_drc.log

This calls a tcl file ‘magic_drc.log’ which creates design rule check report.