disclaims liability for changes, errors or omissions.*
-*Copyright © 2011-2015, Reboot*
+*Copyright © 2011-2017, Reboot*
*All rights reserved.*
AS68 user, before you leap into the unknown please read the section on Notes for
AS68 Users.
-This manual was typeset with TEX and the Computer Modern fonts, and it
-was printed on the Atari SLM-804 laser printer with a MEGA ST. Except for 200
-lines of assembly language, the assembler is written entirely in C.
-
.. [1] It processes 30,000 lines a minute on a lightly loaded VAX 11/780; maybe 40,000 on a 520-ST with an SH-204 hard disk. Yet it could be sped up even more with some effort and without resorting to assembly language; C doesn't have to be slow!
`Getting Started`_
INTIE: ds.l 1
PTSIN: ds.l 1
+ Another interesting example worth mentioning is the emulation of "C"'s "union" keyword
+ using *.abs*. For example, the following "C" code:
+
+ ::
+
+ struct spritesheet
+ {
+ short spf_w;
+ short spf_h;
+ short spf_xo;
+ short spf_yo;
+ union { int spf_em_colour; int spf_emx_colour; };
+ union { int spf_em_psmask[16]; int spf_emx_colouropt; };
+ }
+
+ can be expressed as:
+
+ ::
+
+ .abs
+ *-------------------------------------------------------*
+ spf_w: ds.w 1 ;<- common
+ spf_h: ds.w 1
+ spf_xo: ds.w 1
+ spf_yo: ds.w 1
+ spf_data: ds.l 0
+ *-------------------------------------------------------*
+ ; .union set
+ spf_em_colour: ds.l 1 ;<- union #1
+ spf_em_psmask: ds.l 16
+ *-------------------------------------------------------*
+ .68000
+ .abs spf_em_colour
+ ; .union reset
+ spf_emx_colour: ds.l 1 ;<- union #2
+ spf_emx_colouropt: ds.l 1
+ spf_emx_psmask: ds.l 16
+ spf_emx_psmaskopt: ds.l 16
+
+ .68000
+ ;*-------------------------------------------------------*
+
+ move #spf_em_colour,d0
+ move #spf_emx_colour,d0
+
+ In this example, *spf_em_colour* and *spf_emx_colour* will have the same value.
+
**.comm** *symbol*, *expression*
Specifies a label and the size of a common region. The label is made global,
thus confined symbols cannot be made common. The linker groups all common
*empty* implied or accumulator (e.g. tsx or ror)
*expr* absolute or zeropage
#\ *expr* immediate
+#<\ *expr* immediate low byte of a word
+#>\ *expr* immediate high byte of a word
(*expr*,x) indirect X
(*expr*),y indirect Y
(*expr*) indirect
y,\ *expr* indexed Y
============== ========================================
-While RMAC lacks "high" and "low" operators, high bytes of words may
-be extracted with the shift (``>>``) or divide (``/``) operators, and low bytes may be
-extracted with the bitwise AND (``&``) operator.
-
`6502 Directives`_
''''''''''''''''''
**.6502**
`6502 Object Code Format`_
''''''''''''''''''''''''''
-This is a little bit of a kludge. An object file consists of a page map, followed by
-one or more page images, followed by a normal Alcyon 68000 object file. If the page
-map is all zero, it is not written.
+Traditionally Madmac had a very kludgy way of storing object files. This has been
+replaced with a more standard *.exe* (or *.com* or *.xex* if you prefer). Briefly,
+the *.exe* format consists of chunks of this format (one after the other):
-The page map contains a byte for each of the 256 256-byte pages in the 6502's
-64K address space. The byte is zero (``$00``) if the page contained only zero bytes, or
-one (``$01``) if the page contained any non-zero bytes. If a page is flagged with a one,
-then it is written (in order) following the page map.
-
-The following code:
-
- ::
-
- .6502
- .org $8000
- .dc.b 1
- .org $8100
- .dc.b 1
- .org $8300
- .dc.b 1
- .end
-
-will generate a page map that looks (to a programmer) something like:
-
- ::
+ ::
- <80 bytes of zero>
- 01 01 00 01
- <$7c more bytes of zero, for $100 total>
- <image of page $80>
- <image of page $81>
- <image of page $83>
-
-Following the last page image is an Alcyon-format object file, starting with
-the magic number ``$601a``. It may contain 68000 code (although that is probably
-useless), but the symbol table is valid and available for debugging purposes. 6502
-symbols will be absolute (not in text, data or bss).
+ Offset Description
+ 00-01 $FFFF - Indicates a binary load file. Mandatory for first segment, optional for any other segment
+ 02-03 Start Address. The segment will load at this address
+ 04-05 End Address. The last byte to load for this segment
+ 06-.. The actual segment data to load (End Address-Start Address + 1 bytes)
`Error Messages`_
=================
projects / rmac / blobdiff