ported Brainfuck interpreter.

1 files changed, 68 insertions, 16 deletions

diff --git a/userspace/syscalls.c b/userspace/syscalls.c
index 6547879..d8a463d 100644
--- a/userspace/syscalls.c
+++ b/userspace/syscalls.c
@@ -1,39 +1,79 @@
-
 //printf needs following syscalls: sbrk write close fstat isatty lseek read
 //
 
 #include <sys/stat.h>
+#include <string.h>
+
+static int preread;
+static int alloc;
+easywrite(char *c);
+
+void syscalls_init()
+{
+    preread=0;
+    alloc=0xff0000;
+}
 
 int close(int file) 
 {
-   return -1;
+    easywrite("syscall: close\n");
+    return -1;
 }
 
 int fstat(int file, struct stat *st)
 {
+//    easywrite("syscall: fstat\n");
     st->st_mode = S_IFCHR;
     return 0;
 }
 
-int isatty(int file) {
+int isatty(int file) 
+{
+    easywrite("syscall: isatty\n");
     return 1;
 }
 
-int lseek(int file, int ptr, int dir) {
-    return 0;
+int lseek(int file, int ptr, int dir) 
+{
+//    printf("syscall: lseek %i %i %i",file,ptr,dir);
+    if(dir==0)preread=ptr;
+    else{ puts("other modes unsupported sorry"); while(1);}
+    return preread;
 }
 
-int read(int file, char *ptr, int len) {
-    return 0;
+
+
+int read(int file, char *ptr, int len)
+{
+//    easywrite("syscall: read\n");
+
+    int i;
+    char buf[]="++++++++[>++++[>++>+++>+++>+<<<<-]>+>+>->>+[<]<-]>>.>---.+++++++..+++.>>.<-.<.+++.------.--------.>>+.>++.";
+
+    if(preread>=strlen(buf)){
+	easywrite("syscall: read = EOF\n");
+	while(1);
+	return 0; //EOF
+    }
+
+    for(i=0;i<len;i++)
+    {
+	if(preread>=strlen(buf))return i;
+	ptr[i]=buf[preread++];
+    }
+
+    return len;
 }
-    int open(const char *name, int flags, int mode) {
-	            return -1;
-		              }
 
+int open(const char *name, int flags, int mode)
+{
+    easywrite("syscall: open\n");
+    return 99;
+    return -1;
+}
 
 int write(int file, char *ptr, int len) 
 {
-
     int todo;
     for (todo = 0; todo < len; todo++) 
     {
@@ -58,28 +98,40 @@ int write(int file, char *ptr, int len)
     return len;
 }
 
+
+
 caddr_t sbrk(int incr) 
 {
+	    easywrite("syscall: sbrk!!\n");
+	    int oldalloc=alloc;
+	    alloc+=incr;
+	    return oldalloc;
+	    /*
 	    
-//            extern char _end;		/* Defined by the linker */
-	    char _end;
+            extern char end;	    
+//	    char _end;
             static char *heap_end;
             char *prev_heap_end;
           
             if (heap_end == 0) {
-              heap_end = &_end;
+              heap_end = &end;
             }
             prev_heap_end = heap_end;
-	    /*
+
             if (heap_end + incr > stack_ptr) {
               write (1, "Heap and stack collision\n", 25);
               abort ();
             }
-	    */
           
             heap_end += incr;
             return (caddr_t) prev_heap_end;
+	    */
 }
 
 //
 
+// helpers
+easywrite(char *c)
+{
+    write(1,c,strlen(c));
+}