/* @(#)buf.ss	1.7 11/27/95 17:03:41 */

/****************************************************************
**
** buf.ss
**
** This dc_shell script adds buffers to a net. By calling it
** multiple times you can build a balanced buffer tree, with complete
** control over the type and number of buffers at each level.
**
*****************************************************************
**
** Input variables
**
** what_to_buf          = string, name of object to be buffered
** what_it_is           = string, "net" or "port" or "pin"
** buf_type             = string, name of buffer
** max_loads_per_buf    = integer
** prefix               = string, used to create unique cell and net names
**
*****************************************************************
**
** Example use:
**
**      what_to_buf = "clk"
**      what_it_is = "port"
**      buf_type = "BFX4"
**      max_loads_per_buf = 12
**      prefix = "clkbuf"
**      include -quiet buf.ss
**
*****************************************************************
**
** Caveats
**
** 1. Runs slow if max_loads_per_buf is large.
** 2. All libraries in memory are searched for a cell with
**    the name "buf_type". If you have >1 library with such a
**    cell then the script dies. This might happen if you have a
**    symbol library in memory.
**
*****************************************************************
**
** Future enhancements
**
** 1. automatically determine what_it_is
**
*****************************************************************
**
** Author: Steve Golson, Trilobyte Systems, sgolson@trilobyte.com
**
*****************************************************************/


if (1) {
remove_variable buf$script          ; buf$script = ""
remove_variable buf$thenet          ; buf$thenet = {}
remove_variable buf$thelib          ; buf$thelib = ""
remove_variable buf$thepin          ; buf$thepin = ""
remove_variable buf$thebuf          ; buf$thebuf = {}
remove_variable buf$pin_name        ; buf$pin_name = ""
remove_variable buf$pindir          ; buf$pindir = ""
remove_variable buf$input_pin       ; buf$input_pin = ""
remove_variable buf$output_pin      ; buf$output_pin = ""
remove_variable buf$theloads        ; buf$theloads = {}
remove_variable buf$num_of_loads    ; buf$num_of_loads = 0
remove_variable buf$temp            ; buf$temp = ""
remove_variable buf$numerator       ; buf$numerator = 0
remove_variable buf$denominator     ; buf$denominator = 0
remove_variable buf$quotient_float  ; buf$quotient_float = 0.0
remove_variable buf$quotient        ; buf$quotient = 0
remove_variable buf$remainder       ; buf$remainder = 0
remove_variable buf$num_of_bufs     ; buf$num_of_bufs = 0
remove_variable buf$num_of_loads_per_buf
                                    ; buf$num_of_loads_per_buf = 0
remove_variable buf$num_of_bufs_with_extra_load
                                    ; buf$num_of_bufs_with_extra_load = 0
remove_variable buf$num_of_loads_for_this_buf
                                    ; buf$num_of_loads_for_this_buf = 0
remove_variable buf$cellnum         ; buf$cellnum = 0
remove_variable buf$cellname        ; buf$cellname = ""
remove_variable buf$cellprefix      ; buf$cellprefix = prefix + "cell"
remove_variable buf$netnum          ; buf$netnum = 0
remove_variable buf$netname         ; buf$netname = ""
remove_variable buf$netprefix       ; buf$netprefix = prefix + "net"
remove_variable buf$loads_for_current_buf
                                    ; buf$loads_for_current_buf = {}
remove_variable buf$num_of_loads_for_current_buf
                                    ; buf$num_of_loads_for_current_buf = 0
remove_variable buf$thisload        ; buf$thisload = ""
} > /dev/null

buf$script = "buf.ss"

echo ###### Beginning buf$script to buffer what_it_is what_to_buf

/* bogus "while" so we can use break to abort the script */
while (1) {

if ((what_it_is != "net") && (what_it_is != "port") && (what_it_is != "pin")) {
    echo "ERROR! what_it_is must be \"net\", \"pin\", or \"port\""
    break
    }

if (! find(what_it_is,what_to_buf)) {
    echo "ERROR! Couldn't find" what_it_is what_to_buf
    break
    }

if (max_loads_per_buf <= 0) {
    echo "ERROR! max_loads_per_buf must be positive:" max_loads_per_buf
    break
    }

/**** get the net ****/

if (what_it_is == "net") {
	buf$thenet = what_to_buf
} else {
	buf$thenet = all_connected(find(what_it_is,what_to_buf))
	}

/**** search all libraries to find buf_type input pin and output pin ****/

/* this dies if you have two libraries with the same name (e.g. symbol lib) */

foreach (buf$thelib, find(library)) {
    foreach (buf$thepin, find(lib_pin, buf$thelib + "/" + buf_type + "/*")) {

        buf$thebuf = find(lib_cell, buf$thelib + "/" + buf_type)

        buf$pin_name = buf$thelib + "/" + buf_type + "/" + buf$thepin
        buf$pindir = get_attribute(buf$pin_name, pin_direction)

        if (buf$pindir == {in}) {
            buf$input_pin = buf$thepin
        } else {
            buf$output_pin = buf$thepin
            }
        }
    } > /dev/null

if (buf$thebuf == {}) {
    echo "ERROR! Couldn't find buffer" buf_type
    break
    }

echo ### The buffer is buf$thebuf
echo ### The input pin is buf$input_pin
echo ### The output pin is buf$output_pin

/**** count the number of loads ****/

/* a load is an input pin or an output port that is connected to buf$thenet */

/* the bogus subtract of "0" is needed because the outermost find may have a null */
/* object list, and thus returns a failure code of 0 which gets added to the list */

buf$theloads = \
	  filter( find(port,all_connected(find(net,buf$thenet))), "@port_direction==out") \
	+ filter( find(pin, all_connected(find(net,buf$thenet))), "@pin_direction==in") \
	- "0" > /dev/null

buf$num_of_loads = 0
foreach (buf$temp, buf$theloads) { buf$num_of_loads = buf$num_of_loads + 1 ; }

/**** calculate the number of buffers ****/

/* num_of_bufs = num_of_loads / max_loads_per_buf */
buf$numerator = buf$num_of_loads
buf$denominator = max_loads_per_buf

/* divide, and coerce to float */
if (buf$denominator == 0) { echo "ERROR! Cannot divide by zero!" ; break ; }
buf$quotient_float = (buf$numerator + 0.0) / buf$denominator
/* get the integer quotient */
buf$quotient = buf$quotient_float
/* get the integer remainder */
buf$remainder = 0.5 + (buf$quotient_float - buf$quotient) * buf$denominator

buf$num_of_bufs = buf$quotient

/* need an extra buf if it doesn't come out even */
if (buf$remainder != 0) { buf$num_of_bufs = buf$num_of_bufs + 1 ; }

echo ###### Total of buf$num_of_bufs buffers for buf$num_of_loads loads

/* num_of_loads_per_buf = num_of_loads / num_of_bufs */
buf$numerator = buf$num_of_loads
buf$denominator = buf$num_of_bufs

/* divide, and coerce to float */
if (buf$denominator == 0) { echo "ERROR! Cannot divide by zero!" ; break ; }
buf$quotient_float = (buf$numerator + 0.0) / buf$denominator
/* get the integer quotient */
buf$quotient = buf$quotient_float
/* get the integer remainder */
buf$remainder = 0.5 + (buf$quotient_float - buf$quotient) * buf$denominator

buf$num_of_loads_per_buf = buf$quotient
buf$num_of_bufs_with_extra_load = buf$remainder

echo ### Loads per buf is buf$num_of_loads_per_buf
echo ### There are buf$num_of_bufs_with_extra_load bufs with an extra load

buf$cellnum = 0
buf$netnum = 0

buf$loads_for_current_buf = {}
buf$num_of_loads_for_current_buf = 0

if (buf$num_of_bufs_with_extra_load > 0) {
    buf$num_of_loads_for_this_buf = buf$num_of_loads_per_buf + 1
    buf$num_of_bufs_with_extra_load = buf$num_of_bufs_with_extra_load - 1
} else {
    buf$num_of_loads_for_this_buf = buf$num_of_loads_per_buf
    }

foreach (buf$thisload, buf$theloads) {
    buf$loads_for_current_buf = buf$thisload + buf$loads_for_current_buf
    buf$num_of_loads_for_current_buf = buf$num_of_loads_for_current_buf + 1

    if (buf$num_of_loads_for_current_buf == buf$num_of_loads_for_this_buf) {

        /* get unique cellname */
        buf$cellname = buf$cellprefix + buf$cellnum
        while (find(cell,buf$cellname)) {
            buf$cellnum = buf$cellnum + 1
            buf$cellname = buf$cellprefix + buf$cellnum
            } > /dev/null

        echo ###### Building buffer buf$cellname of type buf$thebuf \
            with buf$num_of_loads_for_this_buf loads...
        create_cell buf$cellname buf$thebuf

        /* wire up the cell input to thenet */
        connect_net buf$thenet find(pin,buf$cellname + "/" + buf$input_pin)

        /* get unique netname */
        buf$netname = buf$netprefix + buf$netnum
        while (find(net,buf$netname)) {
            buf$netnum = buf$netnum + 1
            buf$netname = buf$netprefix + buf$netnum
            } > /dev/null

        create_net buf$netname

        /* remove loads from thenet */
        disconnect_net buf$thenet buf$loads_for_current_buf

        /* connect loads to netname */
        connect_net buf$netname buf$loads_for_current_buf + \
            find(pin,buf$cellname + "/" + buf$output_pin)

        buf$loads_for_current_buf = {}
        buf$num_of_loads_for_current_buf = 0

        if (buf$num_of_bufs_with_extra_load > 0) {
            buf$num_of_loads_for_this_buf = buf$num_of_loads_per_buf + 1
            buf$num_of_bufs_with_extra_load = \
                buf$num_of_bufs_with_extra_load - 1
        } else {
            buf$num_of_loads_for_this_buf = buf$num_of_loads_per_buf
            }
        }
    }

echo ###### buf$script is finished.
break
}

if (1) {
remove_variable buf$script
remove_variable buf$thenet
remove_variable buf$thelib
remove_variable buf$thepin
remove_variable buf$thebuf
remove_variable buf$pin_name
remove_variable buf$pindir
remove_variable buf$input_pin
remove_variable buf$output_pin
remove_variable buf$theloads
remove_variable buf$num_of_loads
remove_variable buf$temp
remove_variable buf$numerator
remove_variable buf$denominator
remove_variable buf$quotient_float
remove_variable buf$quotient
remove_variable buf$remainder
remove_variable buf$num_of_bufs
remove_variable buf$num_of_loads_per_buf
remove_variable buf$num_of_bufs_with_extra_load
remove_variable buf$num_of_loads_for_this_buf
remove_variable buf$cellnum
remove_variable buf$cellname
remove_variable buf$cellprefix
remove_variable buf$netnum
remove_variable buf$netname
remove_variable buf$netprefix
remove_variable buf$loads_for_current_buf
remove_variable buf$num_of_loads_for_current_buf
remove_variable buf$thisload
} > /dev/null