x86: sbrdsp: implement SSE neg_odd_64

Timing on Arrandale:
        C   SSE
Win32:  57   44
Win64:  47   38
Unrolling and not storing mask both save some cycles.
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/x86/sbrdsp.asm

@@ -24,6 +24,7 @@
 SECTION_RODATA
 ; mask equivalent for multiply by -1.0 1.0
 ps_mask         times 2 dd 1<<31, 0
+ps_mask2        times 2 dd 0, 1<<31
 ps_neg          times 4 dd 1<<31
 
 SECTION_TEXT
@@ -220,3 +221,24 @@ cglobal sbr_qmf_post_shuffle, 2,3,4,W,z
     cmp               zq, r2q
     jl             .loop
     REP_RET
+
+INIT_XMM sse
+cglobal sbr_neg_odd_64, 1,2,4,z
+    lea       r1q, [zq+256]
+.loop:
+    mova       m0, [zq+ 0]
+    mova       m1, [zq+16]
+    mova       m2, [zq+32]
+    mova       m3, [zq+48]
+    xorps      m0, [ps_mask2]
+    xorps      m1, [ps_mask2]
+    xorps      m2, [ps_mask2]
+    xorps      m3, [ps_mask2]
+    mova  [zq+ 0], m0
+    mova  [zq+16], m1
+    mova  [zq+32], m2
+    mova  [zq+48], m3
+    add        zq, 64
+    cmp        zq, r1q
+    jne     .loop
+    REP_RET

libavcodec/x86/sbrdsp_init.c

@@ -33,6 +33,7 @@ void ff_sbr_hf_gen_sse(float (*X_high)[2], const float (*X_low)[2],
                        const float alpha0[2], const float alpha1[2],
                        float bw, int start, int end);
 void ff_sbr_qmf_post_shuffle_sse(float W[32][2], const float *z);
+void ff_sbr_neg_odd_64_sse(float *z);
 
 av_cold void ff_sbrdsp_init_x86(SBRDSPContext *s)
 {
@@ -44,5 +45,6 @@ av_cold void ff_sbrdsp_init_x86(SBRDSPContext *s)
         s->hf_g_filt  = ff_sbr_hf_g_filt_sse;
         s->hf_gen     = ff_sbr_hf_gen_sse;
         s->qmf_post_shuffle = ff_sbr_qmf_post_shuffle_sse;
+        s->neg_odd_64 = ff_sbr_neg_odd_64_sse;
     }
 }