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doc/pascal/rtl.doc

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+.sp 1.5i
+.ft B
+Appendix B: Changes to the run time library
+.ft R
+.nh
+.sp
+Some minor changes in the run time library have been made concerning the
+external files (i.e. program arguments). The old compiler reserved
+space for the file structures of the external files in one \fBhol\fR block.
+In the new compiler, every file structure is placed in a separate \fBbss\fR
+block. This implies that the arguments with which \fI_ini\fR is called are
+slightly different. The second argument was the base of the \fBhol\fR block
+to relocate the buffer addresses, it is changed into an integer denoting the
+size of the array passed as third argument. The third argument was a pointer
+to an array of integers containing the description of external files, this
+argument is changed into a pointer to an array of pointers to file structures.
+
+The differences in the generated EM code for an arbitrary Pascal program are
+listed below (only the relevant parts are shown):
+.in +5m
+.nf
+\fBprogram\fR external_files(output,f);
+\fBvar\fR
+	f : \fBfile of \fIsome-type\fR;
+   .
+   .
+\fBend\fR.
+.in -5m
+
+EM code generated by Pascal-VU:
+.in +5m
+   .
+   .
+ hol 1088,-2147483648,0    ; space belonging to file structures of the program arguments
+   .
+   .
+   .
+\&.2
+ con 3, -1, 544, 0         \h'80u'; description of external files
+ lxl 0
+ lae .2
+ lae 0                     \h'146u'; base of hol block, to relocate buffer addresses
+ lxa 0
+ cal $_ini
+ asp 16
+   .
+   .
+.in -5m
+
+EM code generated by our compiler:
+.in +5m
+   .
+   .
+f
+ bss 540,0,0               \h'100u'; space belonging to file structure of program argument f
+output
+ bss 540,0,0               \h'100u'; space belonging to file structure of standard output
+   .
+   .
+   .
+\&.2
+ con 0U4, output, f        \h'50u'; the absence of standard input is denoted by a null pointer
+ lxl 0
+ lae .2
+ loc 3                     \h'144u'; denotes the size of the array of pointers to file structures
+ lxa 0
+ cal $_ini
+ asp 16
+   .
+   .
+.in -5m
+
+.po
+The following files in the run time library have been changed:
+.in +1m
+pc_file.h
+hlt.c
+ini.c
+opn.c
+pentry.c
+pexit.c
+.in -1m
+.fi
+.bp
+.po