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Diffstat (limited to 'module/language/sassy/flat-bin.scm')
| -rw-r--r-- | module/language/sassy/flat-bin.scm | 163 |
1 files changed, 163 insertions, 0 deletions
diff --git a/module/language/sassy/flat-bin.scm b/module/language/sassy/flat-bin.scm new file mode 100644 index 000000000..410f4573b --- /dev/null +++ b/module/language/sassy/flat-bin.scm @@ -0,0 +1,163 @@ +; flat-bin.scm - create bin files from Sassy's output +; Copyright (C) 2005 Jonathan Kraut + +; This library is free software; you can redistribute it and/or +; modify it under the terms of the GNU Lesser General Public +; License as published by the Free Software Foundation; either +; version 2.1 of the License, or (at your option) any later version. + +; This library is distributed in the hope that it will be useful, +; but WITHOUT ANY WARRANTY; without even the implied warranty of +; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU +; Lesser General Public License for more details. + +; You should have received a copy of the GNU Lesser General Public +; License along with this library; if not, write to the Free Software +; Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA + +; Contact: +; Jonathan Kraut +; 4130 43 ST #C2 +; Sunnyside, NY 11104 +; jak76@columbia.edu + +; see file COPYING in the top of Sassy's distribution directory + + +; module flat-bin +; import api +; export all + + + +; This is a good demonstration of how to use the output API, and we +; should probably include it in chapter 7 of the docs. + +; usage: + +; procedure: +; (sassy-make-bin output-file sassy-output opts ...) => unspecified + +; Combines the text and data sections of sassy-output and writes a +; flat binary file to output-file. If the file already exists it is +; deleted. Any (org) directive is taken into account, and relocations +; are performed on absolute references in the data section. The data +; segment is placed (and aligned properly) immediately after the text +; segment. + +; opts can be none, one or both of the following quoted symbols: + +; 'boot : Make the file be an x86 boot-sector. That is, zero-fill the +; remainder of the file to 510 bytes, and add the x86 boot-sector +; signature #x55aa to bytes 511 and 512. + +; 'stats : Display some stats about the output. + + + +(define (sassy-make-bin output-file sassy-output . opts) + + (define boot-sector? (memq 'boot opts)) + (define stats? (memq 'stats opts)) + + (define data? (not (zero? (sassy-data-size sassy-output)))) + + ; Grap some info for printout stats later. + + (define text-size (sassy-text-size sassy-output)) + (define data-size (sassy-data-size sassy-output)) + (define text-pad 0) + + (define (display-stat . itms) + (for-each display itms) + (newline)) + + (define (needed-reloc? x) + (and (eq? 'abs (sassy-reloc-type x)) + (let ((name (sassy-reloc-name x))) + (if name + (let ((symbol (sassy-symbol-exists? sassy-output name))) + (and (eq? 'data (sassy-symbol-section symbol)) + (not (eq? 'import (sassy-symbol-scope symbol))))) + (eq? 'data (sassy-reloc-section x)))))) + + ; Align the end of the text-section to the align of the data section. + ; The data section will begin at this point in the file. + ; (nop) is used as the filler. + + (when data? + (push-stack-align (sassy-text-stack sassy-output) + (sassy-data-align sassy-output) + #x90)) + + (set! text-pad (- (sassy-text-size sassy-output) text-size)) + + ; Since the text-section is going to be loaded at whatever the given + ; (org) was, all absolute relocations in the text section that refer + ; to other locations in the text section already have the offset of + ; (org) added to them, so we don't have to apply relocations to + ; those. And we don't need to relocate relative addresses in the + ; text section (and relative relocations aren't allowed in the data + ; section). + + ; So, we only need to relocate references to symbols defined in the data + ; section, or anonymous relocs in the data section + + ; Also, we need to grab all those references both from the + ; text-section _and_ the _data_ section + + (when data? + (let ((data-relocs-to-do + (filter needed-reloc? (sassy-reloc-list sassy-output)))) + + ; Now we get ready to apply the relocations taking into account the new + ; end of the text-section (or beginning of the data-section). + + ; For each reloc-to-do, we're going to apply it's patcher + ; to the the data-offset plus the value already there + + (let* ((text-offset (sassy-text-org sassy-output)) + (data-offset (+ text-offset (sassy-text-size sassy-output)))) + (for-each (lambda (reloc) + ((sassy-reloc-patcher reloc) + (+ data-offset (sassy-reloc-value reloc)))) + data-relocs-to-do)) + + ; Now all we have to to is append the data to the text, mark it as + ; a boot sectior, and spit it out. + + ; The fastest way to tack a data section on to a text section is + ; the following + ; !!!!NOTE: This actually alters the text section (append!) + (push-stack-append! (sassy-text-stack sassy-output) + (sassy-data-stack sassy-output)))) + + (when boot-sector? + ; sanity check + (if (> (sassy-text-size sassy-output) 510) + (error "segment too big for a boot sector") + (begin + ; mark it as a boot sector + (push-stack-align (sassy-text-stack sassy-output) 510 0) + (push-stack-push (sassy-text-stack sassy-output) + (list #x55 #xaa))))) + + ; dump to file + (when (file-exists? output-file) + (delete-file output-file)) + (with-output-to-file output-file + (lambda () + (for-each write-byte (sassy-text-list sassy-output)))) + + (when stats? + (display-stat "Text size: " text-size " bytes") + (display-stat "Data size: " data-size " bytes") + (display-stat "Data align: " + (sassy-data-align sassy-output) + " byte boundary") + (display-stat + "Total size: " + (+ text-size data-size text-pad) + " bytes, with " text-pad " bytes of padding in the text section.") + (when boot-sector? + (display-stat "Made a boot sector")))) |