1 files changed, 250 insertions, 0 deletions
diff --git a/util/Offsets.c b/util/Offsets.c
new file mode 100644
index 0000000..3cf5a46
--- /dev/null
+++ b/util/Offsets.c
@@ -0,0 +1,250 @@
+/*
+** SCCS ID:	@(#)Offsets.c	2.2	1/23/25
+**
+** @file	Offsets.c
+**
+** @author	Warren R. Carithers
+**
+** Print byte offsets for fields in various structures.
+**
+** This program exists to simplify life.  If/when fields in a structure
+** are changed, this can be modified, recompiled and executed to come up with
+** byte offsets for use in accessing structure fields from assembly language.
+** It makes use of the C 'offsetof' macro (defined since C89).
+**
+** IMPORTANT NOTE:  compiling this on a 64-bit architecture will yield
+** incorrect results by default, as 64-bit GCC versions most often use
+** the LP64 model (longs and pointers are 64 bits).  Add the "-mx32"
+** option to the compiler (compile for x86_64, but use 32-bit sizes),
+** and make sure you have the 'libc6-dev-i386' package installed (for
+** Ubuntu systems).
+**
+** WATCH FOR clashes with standard system functions; compile with the
+** "-fno-builtin" option to avoid warnings about clashes with builtin
+** function declarations.
+**
+** Writes to stdout. Output contains information about type sizes and
+** byte offsets for fields within structures.  If invoked with the -h
+** option, the output takes the form of a standard C header file; 
+** otherwise, the information is printed in ordinary text form.
+**
+** If compiled with the CREATE_HEADER_FILE macro defined, when invoked
+** with the -h option, writes the data directly into a file named
+** "offsets.h".
+*/
+
+// make sure we get all the kernel stuff
+#define KERNEL_SRC
+
+// include any of our headers that define data structures to be described
+#include <common.h>
+#include <procs.h>
+
+// avoid complaints about NULL from stdio.h
+#ifdef NULL
+#undef NULL
+#endif
+
+#include <stdio.h>
+#include <stddef.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+/*
+** We don't include <time.h> because of conflicts with a time_t data
+** type we may be defining; instead, we provide our own prototypes for
+** ctime() and time().
+*/
+
+extern char *ctime( const __time_t *timep );
+extern __time_t time( __time_t *tloc );
+
+/*
+** Header comment, including header guard
+**
+** No newline on the "Creation date" line, because ctime()
+** puts a newline at the end of the string it produces.
+*/
+char h_prefix[] = "/**\n"
+"** @file\toffsets.h\n"
+"**\n"
+"** GENERATED AUTOMATICALLY - DO NOT EDIT\n"
+"**\n"
+"** Creation date: %s"
+"**\n"
+"** This header file contains C Preprocessor macros which expand\n"
+"** into the byte offsets needed to reach fields within structs\n"
+"** used in the baseline system.  Should those struct declarations\n"
+"** change, the Offsets program should be modified (if needed),\n"
+"** recompiled, and re-run to recreate this file.\n"
+"*/\n"
+"\n"
+"#ifndef OFFSETS_H_\n"
+"#define OFFSETS_H_\n";
+
+/*
+** Header guard suffix
+*/
+char h_suffix[] = "\n"
+"#endif\n";
+
+// are we generating the .h file?
+int genheader = 0;
+
+// header file stream
+FILE *hfile;
+
+// prefix for header file lines
+
+// produce a report line
+void process( const char *sname, const char *field, size_t bytes ) {
+	if( genheader ) {
+		char name[64];
+		sprintf( name, "%s_%s", sname, field );
+		fprintf( hfile, "#define\t%-23s\t%u\n", name, bytes );
+	} else {
+		printf( "  %-10s  %u\n", field, bytes );
+	}
+}
+
+#ifdef CREATE_HEADER_FILE
+// dump out the header
+void setheader( void ) {
+	// trigger output into the header file
+	genheader = 1;
+
+	hfile = fopen( "offsets.h", "w" );
+	if( hfile == NULL ) {
+		perror( "offsets.h" );
+		exit( 1 );
+	}
+
+	__time_t t;
+	(void) time( &t );
+
+	fprintf( hfile, h_prefix, ctime(&t) );
+}
+#endif  /* CREATE_HEADER_FILE */
+
+// introduce an "offsets" section for structs
+void hsection( const char *name, const char *typename, size_t size ) {
+	if( genheader ) {
+		fprintf( hfile, "\n// %s structure\n\n", typename );
+		process( "SZ", name, size );
+		fputc( '\n', hfile );
+	} else {
+		printf( "Offsets into %s (%u bytes):\n", typename, size );
+	}
+}
+
+// introduce a "sizes" section for types
+void tsection( const char *name, const char *typename ) {
+	if( genheader ) {
+		fprintf( hfile, "\n// Sizes of %s types\n\n", typename );
+	} else {
+		printf( "Sizes of %s types:\n", typename );
+	}
+}
+
+int main( int argc, char *argv[] ) {
+
+	hfile = stdout;
+
+	if( argc > 1 ) {
+#ifdef CREATE_HEADER_FILE
+		// only accept one argument
+		if( argc == 2 ) {
+			// -h:  produce an offsets.h header file
+			if( argv[1][0] == '-' && argv[1][1] == '-h' ) {
+				setheader();
+			}
+		} else {
+			fprintf( stderr, "usage: %s [-h]\n", argv[0] );
+			exit( 1 );
+		}
+#else
+		// we accept no arguments
+		fprintf( stderr, "usage: %s\n", argv[0] );
+		exit( 1 );
+#endif  /* CREATE_HEADER_FILE */
+	}
+
+	/*
+	** Basic and simple/opaque types
+	*/
+
+	tsection( "SZ", "basic" );
+	process( "SZ", "char", sizeof(char) );
+	process( "SZ", "short", sizeof(short) );
+	process( "SZ", "int", sizeof(int) );
+	process( "SZ", "long", sizeof(long) );
+	process( "SZ", "long_long", sizeof(long long) );
+	process( "SZ", "pointer", sizeof(void *) );
+	fputc( '\n', hfile );
+
+	tsection( "SZ", "our" );
+	process( "SZ", "int8_t", sizeof(int8_t) );
+	process( "SZ", "uint8_t", sizeof(uint8_t) );
+	process( "SZ", "int16_t", sizeof(int16_t) );
+	process( "SZ", "uint16_t", sizeof(uint16_t) );
+	process( "SZ", "int32_t", sizeof(int32_t) );
+	process( "SZ", "uint32_t", sizeof(uint32_t) );
+	process( "SZ", "int64_t", sizeof(int64_t) );
+	process( "SZ", "uint64_t", sizeof(uint64_t) );
+	process( "SZ", "bool_t", sizeof(bool_t) );
+	fputc( '\n', hfile );
+
+	/*
+	** Structured types whose fields we are describing
+	*/
+
+	// add entries for each type here, as needed
+
+	hsection( "CTX", "context_t", sizeof(context_t) );
+	process( "CTX", "ss", offsetof(context_t,ss) );
+	process( "CTX", "gs", offsetof(context_t,gs) );
+	process( "CTX", "fs", offsetof(context_t,fs) );
+	process( "CTX", "es", offsetof(context_t,es) );
+	process( "CTX", "ds", offsetof(context_t,ds) );
+	process( "CTX", "edi", offsetof(context_t,edi) );
+	process( "CTX", "esi", offsetof(context_t,esi) );
+	process( "CTX", "ebp", offsetof(context_t,ebp) );
+	process( "CTX", "esp", offsetof(context_t,esp) );
+	process( "CTX", "ebx", offsetof(context_t,ebx) );
+	process( "CTX", "edx", offsetof(context_t,edx) );
+	process( "CTX", "ecx", offsetof(context_t,ecx) );
+	process( "CTX", "eax", offsetof(context_t,eax) );
+	process( "CTX", "vector", offsetof(context_t,vector) );
+	process( "CTX", "code", offsetof(context_t,code) );
+	process( "CTX", "eip", offsetof(context_t,eip) );
+	process( "CTX", "cs", offsetof(context_t,cs) );
+	process( "CTX", "eflags", offsetof(context_t,eflags) );
+	fputc( '\n', hfile );
+
+	hsection( "SCT", "section_t", sizeof(section_t) );
+	process( "SCT", "length", offsetof(section_t,length) );
+	process( "SCT", "addr", offsetof(section_t,addr) );
+	fputc( '\n', hfile );
+
+	hsection( "PCB", "pcb_t", sizeof(pcb_t) );
+	process( "PCB", "context", offsetof(pcb_t,context) );
+	process( "PCB", "next", offsetof(pcb_t,next) );
+	process( "PCB", "parent", offsetof(pcb_t,parent) );
+	process( "PCB", "wakeup", offsetof(pcb_t,wakeup) );
+	process( "PCB", "exit_status", offsetof(pcb_t,exit_status) );
+	process( "PCB", "pdir", offsetof(pcb_t,pdir) );
+	process( "PCB", "sects", offsetof(pcb_t,sects) );
+	process( "PCB", "pid", offsetof(pcb_t,pid) );
+	process( "PCB", "state", offsetof(pcb_t,state) );
+	process( "PCB", "priority", offsetof(pcb_t,priority) );
+	process( "PCB", "ticks", offsetof(pcb_t,ticks) );
+	fputc( '\n', hfile );
+
+	// finish up the offsets.h file if we need to
+	if( genheader ) {
+		fputs( h_suffix, hfile );
+		fclose( hfile );
+	}
+
+	return( 0 );
+}