6502/cc65
1
0
Fork 0
mirror of https://github.com/cc65/cc65.git synced 2024-12-23 04:30:10 +00:00
Code Issues Projects Releases Wiki Activity

Made corrections according to review comments

Browse Source
This commit is contained in:
Bill Chatfield 2017-07-30 19:51:23 -04:00 committed by GitHub
parent 85e572f4e1
commit 0bd5a8a331
1 changed files with 102 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

105
doc/apple2enh.sgml
View File

@ -519,9 +519,108 @@ url="ca65.html" name="assembler manual">.
<sect1>Specifying file types for fopen<p>
See section
<url url="apple2.html#ss9.4" name="Specifying file types for fopen">
in the apple2 docoumentation.
<descrip>
<tag>Explanation of File Types</tag>
ProDOS associates a file type and an auxiliary type with each file.
These type specifications are separate from the file's name, unlike
Windows which uses the file name's suffix (a.k.a.
extension) to specify the file type. For example, <tt/.exe/,
<tt/.doc/, or <tt/.bat/.
The ProDOS low-level
Machine-Language Interface (MLI) functions for creating and opening
files require these types to be specified. And if they don't match
with the file being opened, the operation may fail.
In contrast, the ISO C function <tt/fopen()/ and the POSIX function
<tt/open()/ have no parameter to specify either a file type or an
auxiliary type. Therefore, some additional mechanism for specifying
the file types is needed.
<tag>Specifying the File Type and Auxiliary Type</tag>
There are two global variables provided that allow the file type
and auxiliary type to be specified before a call to <tt/fopen()/
or <tt/open()/. They are defined in <tt/apple2_filetype.h/:
<tscreen>
<verb>
extern unsigned char _filetype; /* Default: PRODOS_T_BIN */
extern unsigned int _auxtype; /* Default: 0 */
</verb>
</tscreen>
The header file <tt/apple2_filetype.h/ also defines many values
that can be used to set these variables. It is included in
<tt/apple2.h/, which is in turn included in <tt/apple2enh.h/.
So it isn't necessary to include it directly. Just
include one of <tt/apple2.h/ or <tt/apple2enh.h/.
<tag>Example</tag>
A text file cannot be created with just the
standard C functions because they default to the binary type
<tt/PRODOS_T_BIN/. The <tt/_filetype/ variable must be set to
<tt/PRODOS_T_TXT/ to create a text file.
For a text file,
<tt/_auxtype/ specifies the record length. A zero record
length text file is referred to as a sequential text file.
This is equivalent to text files on
other operating systems, except that the line terminator is a
carriage return instead of a line-feed (Linux/BSD/MacOS) or
carriage return, line-feed pair (Windows).
The "sequential" text file terminology is in contrast to a
"random-access" text file which would
have a fixed-length, non-zero record length, so that the
file position of any individual record can be calculated.
For this example, the
<tt/_auxtype/ does not need to be set because it defaults to
the desired value, which is zero. To be more explicit,
<tt/_auxtype/ can also be set to <tt/PRODOS_AUX_T_TXT_SEQ/
which is defined as zero.
<tscreen>
<verb>
&num;include &lt;stdio.h&gt;
&num;include &lt;string.h&gt;
&num;include &lt;errno.h&gt;
&num;include &lt;apple2.h&gt;
void main(void)
{
FILE *out;
char *name = "MY.FAVS";
/*-----------------------------*/
_filetype = PRODOS_T_TXT;
_auxtype = PRODOS_AUX_T_TXT_SEQ;
/*-----------------------------*/
if ((out = fopen(name, "w")) != NULL) {
fputs("Jorah Mormont\r", out);
fputs("Brienne of Tarth\r", out);
fputs("Daenerys Targaryen\r", out);
fputs("Sandor Clegane\r", out);
if (fclose(out) == EOF) {
fprintf(stderr, "fclose failed for %s: %s", name, strerror(errno));
}
}
else {
fprintf(stderr, "fopen failed for %s: %s", name, strerror(errno));
}
}
</verb>
</tscreen>
</descrip><p>