Ghostscript for iVM

In order to be able to render stored PDF files, the virtual machine needs the ability to render PDF files. To achieve this we adapted the Ghostcript open source interpreter for the Postscript and PDF languages. With some modifications, Ghostscript can be run on the ivm64 machine architecture, with Newlib as the C library.

Version of Ghostscript

This is Ghostscript 9.52, modified to run on ivm64.

Prerequisites

The projects ivm-compiler and ivm-implementations must be installed and working. For performance reasons it is necessary to use the C implementation of the ivm64 virtual machine to execute the binary.

Note that below, ivm refers to the standard implementation of ivm64 and vm to the C implementation. For simplicity we assume here that both are in directories in PATH.

Copy PDF input documents

Since GS can't read the PDF documents from standard input, we need to put them into romfs, which is embedded in the executable.

cd ghostscript-9.52
cp -i DOC1.pdf DOC2.pdf DOC3.pdf Resource/Init

Build Ghostscript for ivm64

CC=ivm64-gcc CFLAGS="-DGS_NO_FILESYSTEM -DCMS_NO_PTHREADS" ./configure --host=ivm64 --disable-threading --disable-contrib --disable-fontconfig --disable-dbus --disable-cups --with-drivers=ivm64
make
ivm as --noopt bin/gs

Generate command line arguments file for a given PDF document

echo "bin/gs -sDEVICE=ivm64 -dGraphicsAlphaBits=4 -dTextAlphaBits=4 -r300x300 -dNOPAUSE -dBATCH -dSAFER -sOutputFile=- DOC1.pdf" | tr '[:space:]' '\000' > args

Run Ghostscript:

time vm -o /tmp -a args -m 100000000 bin/gs.b

The output can be found as XXXXXXXX.png files in /tmp.