add some comments to walkcbfs.S

Signed-off-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
Acked-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
git-svn-id: svn://svn.coreboot.org/coreboot/trunk@6498 2b7e53f0-3cfb-0310-b3e9-8179ed1497e1

diff --git a/src/arch/x86/lib/walkcbfs.S b/src/arch/x86/lib/walkcbfs.S
index 27d82ae74221a532a501f6d292f40a2d2fb8f875..2dc9617651b413d0584291cc1c42b06f6134850d 100644 (file)
--- a/src/arch/x86/lib/walkcbfs.S
+++ b/src/arch/x86/lib/walkcbfs.S
@@ -16,11 +16,11 @@
 #define CBFS_FILE_STRUCTSIZE (CBFS_FILE_OFFSET + 4)
 
 /*
-  input %esi: filename
-  input %esp: return address (not pointer to return address!)
-  output %eax: entry point
-  clobbers %ebx, %ecx, %edi
-*/
+ * input %esi: filename
+ * input %esp: return address (not pointer to return address!)
+ * output %eax: entry point
+ * clobbers %ebx, %ecx, %edi
+ */
 walkcbfs_asm:
        cld
 
@@ -28,10 +28,10 @@ walkcbfs_asm:
        mov CBFS_HEADER_ROMSIZE(%eax), %ecx
        bswap %ecx
        mov $0, %ebx
-       sub %ecx, %ebx
+       sub %ecx, %ebx  /* rom base address in ebx */
        mov CBFS_HEADER_OFFSET(%eax), %ecx
        bswap %ecx
-       add %ecx, %ebx
+       add %ecx, %ebx  /* address where we start looking for LARCHIVEs */
 
        /* determine filename length */
        mov $0, %eax
@@ -43,21 +43,22 @@ walkcbfs_asm:
 2:
        add $1, %eax
 walker:
-       mov 0(%ebx), %edi
+       mov 0(%ebx), %edi /* Check for LARCHIVE header */
        cmp %edi, filemagic
        jne searchfile
        mov 4(%ebx), %edi
        cmp %edi, filemagic+4
        jne searchfile
 
+       /* LARCHIVE header found */
        mov %ebx, %edi
        add $CBFS_FILE_STRUCTSIZE, %edi /* edi = address of first byte after struct cbfs_file */
        mov %eax, %ecx
        repe cmpsb
-       # zero flag set if strings are equal
+       /* zero flag set if strings are equal */
        jnz tryharder
 
-       # we found it!
+       /* we found it! */
        mov CBFS_FILE_OFFSET(%ebx), %eax
        bswap %eax
        add %ebx, %eax