xnu-3247.1.106.tar.gz

[apple/xnu.git] / osfmk / x86_64 / WKdmDecompress_new.s

diff --git a/osfmk/x86_64/WKdmDecompress_new.s b/osfmk/x86_64/WKdmDecompress_new.s
index 1c435c5e793a507f74605c37cdd1200c50af2b6f..bcf6496edb924f700099fca69181833e9004e285 100644 (file)
--- a/osfmk/x86_64/WKdmDecompress_new.s
+++ b/osfmk/x86_64/WKdmDecompress_new.s
@@ -64,8 +64,13 @@
                        }
  
        cclee, 11/30/12
+
+    Added zero page, single value page, sparse page, early abort optimizations
+    rsrini, 09/14/14
 */
 
+#define MZV_MAGIC           $17185      // magic value used to identify MZV page encoding
+
        .text
 
        .globl _WKdm_decompress_new
@@ -81,27 +86,61 @@ _WKdm_decompress_new:
 
        subq    $(64+8+16), %rsp
 
+    movl    0(%rdi), %eax               // read the 1st word from the header
+    cmpl    MZV_MAGIC, %eax             // is the alternate packer used (i.e. is MZV page)?
+    jne     L_default_decompressor      // default decompressor was used
+
+                                        // Mostly Zero Page Handling...
+                                        // {
+    movq    $0, %rax
+1:                                      // Zero out the entire page
+    movq    $0, 0(%rsi, %rax)
+    movq    $0, 8(%rsi, %rax)
+    movq    $0, 16(%rsi, %rax)
+    movq    $0, 24(%rsi, %rax)
+    movq    $0, 32(%rsi, %rax)
+    movq    $0, 40(%rsi, %rax)
+    movq    $0, 48(%rsi, %rax)
+    movq    $0, 56(%rsi, %rax)
+    addq    $64, %rax
+    cmpq    $4096, %rax
+    jne     1b
+
+    movq    $4, %r12                    // current byte position in src to read from
+2:
+    movl    0(%rdi, %r12), %eax         // get the word
+    movzwq  4(%rdi, %r12), %rdx         // get the index
+    movl    %eax, 0(%rsi, %rdx)         // store non-0 word in the destination buffer
+    addq    $6, %r12                    // 6 more bytes processed
+    cmpl    %ecx, %r12d                 // finished processing all the bytes?
+    jne     2b
+    jmp     L_done
+                                        // }
+
+L_default_decompressor:
+
        movq    %rsi, %r12                                      // dest_buf
-       movq    %rdx, %r13                                      // scracht_buf
+       movq    %rdx, %r13                                      // scratch_buf
 
        // PRELOAD_DICTONARY; dictionary starting address : starting address 0(%rsp)
+    // NOTE: ALL THE DICTIONARY VALUES MUST BE INITIALIZED TO ZERO TO MIRROR THE COMPRESSOR
 #if 1
-       movl    $1, 0(%rsp)
-       movl    $1, 4(%rsp)
-       movl    $1, 8(%rsp)
-       movl    $1, 12(%rsp)
-       movl    $1, 16(%rsp)
-       movl    $1, 20(%rsp)
-       movl    $1, 24(%rsp)
-       movl    $1, 28(%rsp)
-       movl    $1, 32(%rsp)
-       movl    $1, 36(%rsp)
-       movl    $1, 40(%rsp)
-       movl    $1, 44(%rsp)
-       movl    $1, 48(%rsp)
-       movl    $1, 52(%rsp)
-       movl    $1, 56(%rsp)
-       movl    $1, 60(%rsp)
+       movl    $0, 0(%rsp)
+       movl    $0, 4(%rsp)
+       movl    $0, 8(%rsp)
+       movl    $0, 12(%rsp)
+       movl    $0, 16(%rsp)
+       movl    $0, 20(%rsp)
+       movl    $0, 24(%rsp)
+       movl    $0, 28(%rsp)
+       movl    $0, 32(%rsp)
+       movl    $0, 36(%rsp)
+       movl    $0, 40(%rsp)
+       movl    $0, 44(%rsp)
+       movl    $0, 48(%rsp)
+       movl    $0, 52(%rsp)
+       movl    $0, 56(%rsp)
+       movl    $0, 60(%rsp)
 #else
        mov             $0x100000001, %rax
        mov             %rax, (%rsp)