From 85ef10826f7ebf742349acfc22cdd279db29db7c Mon Sep 17 00:00:00 2001
From: Nils Wallménius <nils@rockbox.org>
Date: Tue, 13 Sep 2011 16:53:13 +0000
Subject: codeclib: tweak coldfire mdct asm a bit more, flip usage of mac/msac
 instead of explicit negation, changes output slightly but is as close to the
 c version as before. Gives about 0.4MHz speedup of vorbis on cf.

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@30516 a1c6a512-1295-4272-9138-f99709370657
---
 apps/codecs/lib/mdct.c | 95 ++++++++++++++++++++++++++++++++++----------------
 1 file changed, 65 insertions(+), 30 deletions(-)

diff --git a/apps/codecs/lib/mdct.c b/apps/codecs/lib/mdct.c
index 621b9cbbb8..5524afbbc4 100644
--- a/apps/codecs/lib/mdct.c
+++ b/apps/codecs/lib/mdct.c
@@ -124,7 +124,6 @@ void ff_imdct_half(unsigned int nbits, fixed32 *output, const fixed32 *input)
         default:
         {
             fixed32 * z1 = (fixed32 *)(&z[0]);
-            fixed32 * z2 = (fixed32 *)(&z[n4-1]);
             int magic_step = step>>2;
             int newstep;
             if(n<=1024)
@@ -137,47 +136,84 @@ void ff_imdct_half(unsigned int nbits, fixed32 *output, const fixed32 *input)
                 T = sincos_lookup1;
                 newstep = 2;
             }
-        
-            while(z1<z2)
-            {
+
 #ifdef CPU_COLDFIRE
+            fixed32 * z2 = (fixed32 *)(&z[n4]);
+            int c = n4;
+            if (newstep == 2)
+            {
                 asm volatile ("movem.l (%[z1]), %%d0-%%d1\n\t"
+                              "addq.l #8, %[z1]\n\t"
                               "movem.l (%[T]), %%d2-%%d3\n\t"
-                              "mac.l %%d1, %%d2, %%acc0\n\t"
-                              "msac.l %%d0, %%d3, %%acc0\n\t"
-                              "mac.l %%d0, %%d2, %%acc1\n\t"
-                              "mac.l %%d1, %%d3, %%acc1\n\t"
+                              "addq.l #8, %[T]\n\t"
+                              "bra.s 1f\n\t"
+                              "0:\n\t"
+                              "msac.l %%d1, %%d2, (%[T])+, %%a3, %%acc0\n\t"
+                              "mac.l  %%d0, %%d3, (%[T])+, %%a4, %%acc0\n\t"
+                              
+                              "msac.l %%d1, %%d3, -(%[z2]), %%d1, %%acc1\n\t"
+                              "msac.l %%d0, %%d2, -(%[z2]), %%d0, %%acc1\n\t"
 
-                              "lea (%[newstep]*4, %[T]), %[T]\n\t"
+                              "msac.l %%d1, %%a4, (%[T])+, %%d2, %%acc2\n\t"
+                              "mac.l  %%d0, %%a3, (%[T])+, %%d3, %%acc2\n\t"
+                              "msac.l %%d0, %%a4, (%[z1])+, %%d0, %%acc3\n\t"
+                              "msac.l %%d1, %%a3, (%[z1])+, %%d1, %%acc3\n\t"
+
+                              "movclr.l %%acc0, %%a3\n\t"
+                              "movclr.l %%acc3, %%a4\n\t"
+                              "movem.l %%a3-%%a4, (-16, %[z1])\n\t"
 
-                              "movem.l (%[z2]), %%d0-%%d1\n\t"
+                              "movclr.l %%acc1, %%a4\n\t"
+                              "movclr.l %%acc2, %%a3\n\t"
+                              "movem.l %%a3-%%a4, (%[z2])\n\t"
+
+                              "subq.l #2, %[n]\n\t"
+                              "1:\n\t"
+                              "bhi.s 0b\n\t"
+                              : [z1] "+a" (z1), [z2] "+a" (z2), [T] "+a" (T), [n] "+d" (c)
+                              :
+                              : "d0", "d1", "d2", "d3", "a3", "a4", "cc", "memory");
+            }
+            else
+            {
+                asm volatile ("movem.l (%[z1]), %%d0-%%d1\n\t"
+                              "addq.l #8, %[z1]\n\t"
                               "movem.l (%[T]), %%d2-%%d3\n\t"
-                              "mac.l %%d1, %%d3, %%acc2\n\t"
-                              "msac.l %%d0, %%d2, %%acc2\n\t"
-                              "mac.l %%d0, %%d3, %%acc3\n\t"
-                              "mac.l %%d1, %%d2, %%acc3\n\t"
+                              "lea (%[newstep]*4, %[T]), %[T]\n\t"
+                              "bra.s 1f\n\t"
+                              "0:\n\t"
+                              "msac.l %%d1, %%d2, (%[T]), %%a3, %%acc0\n\t"
+                              "mac.l  %%d0, %%d3, (4, %[T]), %%a4, %%acc0\n\t"
+                              "msac.l %%d1, %%d3, -(%[z2]), %%d1, %%acc1\n\t"
+                              "msac.l %%d0, %%d2, -(%[z2]), %%d0, %%acc1\n\t"
 
                               "lea (%[newstep]*4, %[T]), %[T]\n\t"
+                              "msac.l %%d1, %%a4, (%[T]), %%d2, %%acc2\n\t"
+                              "mac.l  %%d0, %%a3, (4, %[T]), %%d3, %%acc2\n\t"
+                              "msac.l %%d0, %%a4, (%[z1])+, %%d0, %%acc3\n\t"
+                              "msac.l %%d1, %%a3, (%[z1])+, %%d1, %%acc3\n\t"
 
-                              "movclr.l %%acc0, %%d0\n\t"
-                              "movclr.l %%acc1, %%d2\n\t"
-                              "movclr.l %%acc2, %%d1\n\t"
-                              "movclr.l %%acc3, %%d3\n\t"
+                              "lea (%[newstep]*4, %[T]), %[T]\n\t"
 
-                              "neg.l %%d0\n\t"
-                              "neg.l %%d1\n\t"
-                              "neg.l %%d2\n\t"
-                              "neg.l %%d3\n\t"
+                              "movclr.l %%acc0, %%a3\n\t"
+                              "movclr.l %%acc3, %%a4\n\t"
+                              "movem.l %%a3-%%a4, (-16, %[z1])\n\t"
 
-                              "movem.l %%d0/%%d3, (%[z1])\n\t"
-                              "movem.l %%d1/%%d2, (%[z2])\n\t"
+                              "movclr.l %%acc1, %%a4\n\t"
+                              "movclr.l %%acc2, %%a3\n\t"
+                              "movem.l %%a3-%%a4, (%[z2])\n\t"
 
-                              "addq.l #8, %[z1]\n\t"
-                              "subq.l #8, %[z2]\n\t"
-                              : [z1] "+a" (z1), [z2] "+a" (z2), [T] "+a" (T)
+                              "subq.l #2, %[n]\n\t"
+                              "1:\n\t"
+                              "bhi.s 0b\n\t"
+                              : [z1] "+a" (z1), [z2] "+a" (z2), [T] "+a" (T), [n] "+d" (c)
                               : [newstep] "d" (newstep)
-                              : "d0", "d1", "d2", "d3", "cc", "memory");
+                              : "d0", "d1", "d2", "d3", "a3", "a4", "cc", "memory");
+            }
 #else
+            fixed32 * z2 = (fixed32 *)(&z[n4-1]);
+            while(z1<z2)
+            {
                 fixed32 r0,i0,r1,i1;
                 XNPROD31_R(z1[1], z1[0], T[0], T[1], r0, i1 ); T+=newstep;
                 XNPROD31_R(z2[1], z2[0], T[1], T[0], r1, i0 ); T+=newstep;
@@ -187,9 +223,8 @@ void ff_imdct_half(unsigned int nbits, fixed32 *output, const fixed32 *input)
                 z2[1] = -i1;
                 z1+=2;
                 z2-=2;
-#endif
             }
-            
+#endif 
             break;
         }
 
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