Some more details on W64 stack arguments.

diff --git a/x86_64/README b/x86_64/README
index fe6f2a8b889742144b61858e4f845697cc07d30f..e8cb17b64820f8ee5487afefced1e67efc30a557 100644 (file)
--- a/x86_64/README
+++ b/x86_64/README
@@ -24,7 +24,7 @@ Registers     May be          Argument
 %r14           
 %r15           
 
-w64 ABI, according to
+W64 ABI, according to
 http://msdn.microsoft.com/en-us/library/9z1stfyw.aspx:
 
 Registers      May be          Argument
@@ -51,3 +51,15 @@ Additional arguments are passed on the stack. "backing store" on the
 stack for the four register arguments is also required. %xmm6 to
 %xmm15 are callee-saved. The "long" type is just 32 bits. Nettle
 currently does *NOT* support this ABI.
+
+If we have five arguments, and push the additional callee-save
+registers %rdi and %rsi on the stack, we get a stack frame like
+
+56(%rsp): Fifth argument
+48(%rsp): Space for fourth argument
+40(%rsp): Space for third argument
+32(%rsp): Space for second argument
+24(%rsp): Space for first argument
+16(%rsp): Return address
+8(%rsp): Saved %rsi
+(%rsp) : Saved %rdi