From 3d0ad46eea29876ac56c7843f893a041e658bf4e Mon Sep 17 00:00:00 2001
From: Nicholas <npmazzuca@gmail.com>
Date: Sun, 26 Apr 2015 10:26:56 -0700
Subject: [PATCH 1/3] Fix the inline assembly examples
They now use the currently working syntax.
---
src/doc/trpl/inline-assembly.md | 34 +++++++++++++++++++++++++++++----
1 file changed, 30 insertions(+), 4 deletions(-)
diff --git a/src/doc/trpl/inline-assembly.md b/src/doc/trpl/inline-assembly.md
index 1a4592f980fa7..ab360de62f521 100644
--- a/src/doc/trpl/inline-assembly.md
+++ b/src/doc/trpl/inline-assembly.md
@@ -58,7 +58,7 @@ but you must add the right number of `:` if you skip them:
asm!("xor %eax, %eax"
:
:
- : "eax"
+ : "{eax}"
);
# } }
```
@@ -69,7 +69,7 @@ Whitespace also doesn't matter:
# #![feature(asm)]
# #[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
# fn main() { unsafe {
-asm!("xor %eax, %eax" ::: "eax");
+asm!("xor %eax, %eax" ::: "{eax}");
# } }
```
@@ -83,7 +83,7 @@ expressions must be mutable lvalues:
# #![feature(asm)]
# #[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
fn add(a: i32, b: i32) -> i32 {
- let mut c = 0;
+ let c: i32;
unsafe {
asm!("add $2, $0"
: "=r"(c)
@@ -100,6 +100,21 @@ fn main() {
}
```
+If you would like to use real operands in this position, however,
+you are required to put curly braces `{}` around the register that
+you want, and you are required to put the specific size of the
+operand. This is useful for very low level programming, where
+which register you use is important:
+
+```
+# #[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
+# unsafe fn read_byte_in(port: u16) -> u8 {
+let result: u8;
+asm!("in %dx, %al" : "={al}"(result) : "{dx}"(port));
+result
+# }
+```
+
## Clobbers
Some instructions modify registers which might otherwise have held
@@ -112,7 +127,7 @@ stay valid.
# #[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
# fn main() { unsafe {
// Put the value 0x200 in eax
-asm!("mov $$0x200, %eax" : /* no outputs */ : /* no inputs */ : "eax");
+asm!("mov $$0x200, %eax" : /* no outputs */ : /* no inputs */ : "{eax}");
# } }
```
@@ -139,3 +154,14 @@ Current valid options are:
the compiler to insert its usual stack alignment code
3. *intel* - use intel syntax instead of the default AT&T.
+```
+# #![feature(asm)]
+# #[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
+# fn main() {
+let result: i32;
+unsafe {
+ asm!("mov eax, 2" : "={eax}"(result) : : : "intel")
+}
+println!("eax is currently {}", result);
+# } }
+```
From a70b2ed826d5e51429e035c6924c63c9511afeac Mon Sep 17 00:00:00 2001
From: Nicholas <npmazzuca@gmail.com>
Date: Sun, 26 Apr 2015 10:34:28 -0700
Subject: [PATCH 2/3] Outputs no longer have to be mutable
---
src/doc/trpl/inline-assembly.md | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/src/doc/trpl/inline-assembly.md b/src/doc/trpl/inline-assembly.md
index ab360de62f521..091eadcc9d820 100644
--- a/src/doc/trpl/inline-assembly.md
+++ b/src/doc/trpl/inline-assembly.md
@@ -77,7 +77,7 @@ asm!("xor %eax, %eax" ::: "{eax}");
Input and output operands follow the same format: `:
"constraints1"(expr1), "constraints2"(expr2), ..."`. Output operand
-expressions must be mutable lvalues:
+expressions must be mutable lvalues, or not yet assigned:
```
# #![feature(asm)]
From 766c1bc99283a553fe893469fafa1f7e82ac6157 Mon Sep 17 00:00:00 2001
From: Nicholas <npmazzuca@gmail.com>
Date: Sun, 26 Apr 2015 19:44:44 -0700
Subject: [PATCH 3/3] Fix the errors
---
src/doc/trpl/inline-assembly.md | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/src/doc/trpl/inline-assembly.md b/src/doc/trpl/inline-assembly.md
index 091eadcc9d820..58c2a982dd309 100644
--- a/src/doc/trpl/inline-assembly.md
+++ b/src/doc/trpl/inline-assembly.md
@@ -107,6 +107,7 @@ operand. This is useful for very low level programming, where
which register you use is important:
```
+# #![feature(asm)]
# #[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
# unsafe fn read_byte_in(port: u16) -> u8 {
let result: u8;
@@ -163,5 +164,5 @@ unsafe {
asm!("mov eax, 2" : "={eax}"(result) : : : "intel")
}
println!("eax is currently {}", result);
-# } }
+# }
```