Rewrite the I/O port code.

The contents of these functions was derived from code used in the
Massachusetts Institute of Technology's 6.828 advanced operating
systems course.

I deleted the contents of these functions and then rewrote them from
scratch without reference to the earlier code, working only from the
function comments (which I wrote earlier).

diff --git a/src/threads/io.h b/src/threads/io.h
index b4932995294b684c3a7c822b24224ae91b5a3953..30d52da046ee2faa2d0caac142f67a3730cb9c5f 100644 (file)
--- a/src/threads/io.h
+++ b/src/threads/io.h
@@ -1,43 +1,3 @@
-/* This file is derived from source code used in MIT's 6.828
-   course.  The original copyright notice is reproduced in full
-   below. */
-
-/*
- * Copyright (C) 1997 Massachusetts Institute of Technology 
- *
- * This software is being provided by the copyright holders under the
- * following license. By obtaining, using and/or copying this software,
- * you agree that you have read, understood, and will comply with the
- * following terms and conditions:
- *
- * Permission to use, copy, modify, distribute, and sell this software
- * and its documentation for any purpose and without fee or royalty is
- * hereby granted, provided that the full text of this NOTICE appears on
- * ALL copies of the software and documentation or portions thereof,
- * including modifications, that you make.
- *
- * THIS SOFTWARE IS PROVIDED "AS IS," AND COPYRIGHT HOLDERS MAKE NO
- * REPRESENTATIONS OR WARRANTIES, EXPRESS OR IMPLIED. BY WAY OF EXAMPLE,
- * BUT NOT LIMITATION, COPYRIGHT HOLDERS MAKE NO REPRESENTATIONS OR
- * WARRANTIES OF MERCHANTABILITY OR FITNESS FOR ANY PARTICULAR PURPOSE OR
- * THAT THE USE OF THE SOFTWARE OR DOCUMENTATION WILL NOT INFRINGE ANY
- * THIRD PARTY PATENTS, COPYRIGHTS, TRADEMARKS OR OTHER RIGHTS. COPYRIGHT
- * HOLDERS WILL BEAR NO LIABILITY FOR ANY USE OF THIS SOFTWARE OR
- * DOCUMENTATION.
- *
- * The name and trademarks of copyright holders may NOT be used in
- * advertising or publicity pertaining to the software without specific,
- * written prior permission. Title to copyright in this software and any
- * associated documentation will at all times remain with copyright
- * holders. See the file AUTHORS which should have accompanied this software
- * for a list of all copyright holders.
- *
- * This file may be derived from previously copyrighted software. This
- * copyright applies only to those changes made by the copyright
- * holders listed in the AUTHORS file. The rest of this file is covered by
- * the copyright notices, if any, listed below.
- */
-
 #ifndef THREADS_IO_H
 #define THREADS_IO_H
 
@@ -50,7 +10,7 @@ inb (uint16_t port)
 {
   /* See [IA32-v2a] "IN". */
   uint8_t data;
-  asm volatile ("inb %w1,%0" : "=a" (data) : "d" (port));
+  asm volatile ("inb %w1, %b0" : "=a" (data) : "Nd" (port));
   return data;
 }
 
@@ -60,10 +20,7 @@ static inline void
 insb (uint16_t port, void *addr, size_t cnt)
 {
   /* See [IA32-v2a] "INS". */
-  asm volatile ("cld; repne; insb"
-                : "=D" (addr), "=c" (cnt)
-                : "d" (port), "0" (addr), "1" (cnt)
-                : "memory", "cc");
+  asm volatile ("rep insb" : "+D" (addr), "+c" (cnt) : "d" (port) : "memory");
 }
 
 /* Reads and returns 16 bits from PORT. */
@@ -72,7 +29,7 @@ inw (uint16_t port)
 {
   uint16_t data;
   /* See [IA32-v2a] "IN". */
-  asm volatile ("inw %w1,%0" : "=a" (data) : "d" (port));
+  asm volatile ("inw %w1, %w0" : "=a" (data) : "Nd" (port));
   return data;
 }
 
@@ -82,10 +39,7 @@ static inline void
 insw (uint16_t port, void *addr, size_t cnt)
 {
   /* See [IA32-v2a] "INS". */
-  asm volatile ("cld; repne; insw"
-                : "=D" (addr), "=c" (cnt)
-                : "d" (port), "0" (addr), "1" (cnt)
-                : "memory", "cc");
+  asm volatile ("rep insw" : "+D" (addr), "+c" (cnt) : "d" (port) : "memory");
 }
 
 /* Reads and returns 32 bits from PORT. */
@@ -94,7 +48,7 @@ inl (uint16_t port)
 {
   /* See [IA32-v2a] "IN". */
   uint32_t data;
-  asm volatile ("inl %w1,%0" : "=a" (data) : "d" (port));
+  asm volatile ("inl %w1, %0" : "=a" (data) : "Nd" (port));
   return data;
 }
 
@@ -104,10 +58,7 @@ static inline void
 insl (uint16_t port, void *addr, size_t cnt)
 {
   /* See [IA32-v2a] "INS". */
-  asm volatile ("cld; repne; insl"
-                : "=D" (addr), "=c" (cnt)
-                : "d" (port), "0" (addr), "1" (cnt)
-                : "memory", "cc");
+  asm volatile ("rep insl" : "+D" (addr), "+c" (cnt) : "d" (port) : "memory");
 }
 
 /* Writes byte DATA to PORT. */
@@ -115,7 +66,7 @@ static inline void
 outb (uint16_t port, uint8_t data)
 {
   /* See [IA32-v2b] "OUT". */
-  asm volatile ("outb %0,%w1" : : "a" (data), "d" (port));
+  asm volatile ("outb %b0, %w1" : : "a" (data), "Nd" (port));
 }
 
 /* Writes to PORT each byte of data in the CNT-byte buffer
@@ -124,10 +75,7 @@ static inline void
 outsb (uint16_t port, const void *addr, size_t cnt)
 {
   /* See [IA32-v2b] "OUTS". */
-  asm volatile ("cld; repne; outsb"
-                : "=S" (addr), "=c" (cnt)
-                : "d" (port), "0" (addr), "1" (cnt)
-                : "cc");
+  asm volatile ("rep outsb" : "+S" (addr), "+c" (cnt) : "d" (port));
 }
 
 /* Writes the 16-bit DATA to PORT. */
@@ -135,7 +83,7 @@ static inline void
 outw (uint16_t port, uint16_t data)
 {
   /* See [IA32-v2b] "OUT". */
-  asm volatile ("outw %0,%w1" : : "a" (data), "d" (port));
+  asm volatile ("outw %w0, %w1" : : "a" (data), "Nd" (port));
 }
 
 /* Writes to PORT each 16-bit unit (halfword) of data in the
@@ -144,10 +92,7 @@ static inline void
 outsw (uint16_t port, const void *addr, size_t cnt)
 {
   /* See [IA32-v2b] "OUTS". */
-  asm volatile ("cld; repne; outsw"
-                : "=S" (addr), "=c" (cnt)
-                : "d" (port), "0" (addr), "1" (cnt)
-                : "cc");
+  asm volatile ("rep outsw" : "+S" (addr), "+c" (cnt) : "d" (port));
 }
 
 /* Writes the 32-bit DATA to PORT. */
@@ -155,7 +100,7 @@ static inline void
 outl (uint16_t port, uint32_t data)
 {
   /* See [IA32-v2b] "OUT". */
-  asm volatile ("outl %0,%w1" : : "a" (data), "d" (port));
+  asm volatile ("outl %0, %w1" : : "a" (data), "Nd" (port));
 }
 
 /* Writes to PORT each 32-bit unit (word) of data in the CNT-word
@@ -164,10 +109,7 @@ static inline void
 outsl (uint16_t port, const void *addr, size_t cnt)
 {
   /* See [IA32-v2b] "OUTS". */
-  asm volatile ("cld; repne; outsl"
-                : "=S" (addr), "=c" (cnt)
-                : "d" (port), "0" (addr), "1" (cnt)
-                : "cc");
+  asm volatile ("rep outsl" : "+S" (addr), "+c" (cnt) : "d" (port));
 }
 
 #endif /* threads/io.h */