pad: fix test and update README to reflect the new base rotations

Signed-off-by: Peter Gadfort <[email protected]>

src/pad/README.md

@@ -167,7 +167,7 @@ make_io_sites
 | `-vertical_site` | Name of the site for the vertical pads (north and south). |
 | `-corner_site` | Name of the site for the corner cells. |
 | `-offset` | Offset from the die edge to place the rows. |
-| `-rotation_horizontal` | Rotation to apply to the horizontal sites to ensure pads are placed correctly. The default value is `R0` for the eastern (right) row. |
+| `-rotation_horizontal` | Rotation to apply to the horizontal sites to ensure pads are placed correctly. The default value is `R0` for the western (left) row when different sites are specified for hortizontal and vertical rows, the default value is `MXR90` when the same site is specified. |
 | `-rotation_vertical` | Rotation to apply to the vertical sites to ensure pads are placed correctly. The default value is `R0` for the southern (bottom) row. |
 | `-rotation_corner` | Rotation to apply to the corner sites to ensure pads are placed correctly. The default value is `R0` for the south west (lower left) corner. |
 | `-ring_index` | Used to specify the index of the ring in case of multiple rings. |

src/pad/test/make_io_sites_rotations.tcl

@@ -9,7 +9,7 @@ read_def Nangate45_blackparrot/floorplan.def
 
 # Test make_io_sites
 make_io_sites -horizontal_site IOSITE -vertical_site IOSITE2 -corner_site IOSITE -offset 15 \
-    -rotation_horizontal R90 \
+    -rotation_horizontal MXR90 \
     -rotation_vertical MY
 
 set def_file [make_result_file "make_io_sites_rotations.def"]