Use all available codec iram for reciprocal table in APE codec on ARMv4. Done by linking first with the table empty to determine free space, then sizing table to fill it.

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@24507 a1c6a512-1295-4272-9138-f99709370657

1 files changed, 29 insertions, 13 deletions

diff --git a/apps/codecs/demac/libdemac/udiv32_arm.S b/apps/codecs/demac/libdemac/udiv32_arm.S
index 4492492d30..939fce17d4 100644
--- a/apps/codecs/demac/libdemac/udiv32_arm.S
+++ b/apps/codecs/demac/libdemac/udiv32_arm.S
@@ -29,6 +29,13 @@
  ****************************************************************************/
 
 #include "config.h"
+/* On targets with codec iram, a header file will be generated after an initial
+   link of the APE codec, stating the amount of IRAM remaining for use by the
+   reciprocal lookup table. */
+#if !defined(APE_PRE) && defined(USE_IRAM) && ARM_ARCH < 5
+#include "apps/codecs/ape_free_iram.h"
+#endif
+
 /* Codecs should not normally do this, but we need to check a macro, and
  * codecs.h would confuse the assembler. */
 
@@ -88,20 +95,29 @@
     eor     \quotient, \result, \remainder, lsl \bits
 .endm
 
-#ifdef CPU_PP
-#if CONFIG_CPU == PP5020
-.set recip_max, 8384
-#elif CONFIG_CPU == PP5002
-.set recip_max, 4608
+#ifndef FREE_IRAM
+.set recip_max, 2
 #else
-.set recip_max, 16384
-#endif
-#elif CONFIG_CPU == AS3525
-.set recip_max, 42752
-#elif CONFIG_CPU == S5L8701
-.set recip_max, 12800
-#elif CONFIG_CPU == S5L8700
-.set recip_max, 9088
+/* Each table entry is one word. Since a compare is done against the maximum
+   entry as an immediate, the maximum entry must be a valid ARM immediate,
+   which means a byte shifted by an even number of places. */
+.set recip_max, 2 + FREE_IRAM / 4
+.set recip_max_tmp, recip_max >> 8
+.set recip_mask_shift, 0
+.set tmp_shift, 16
+.rept 5
+    .if recip_max_tmp >> tmp_shift
+        .set recip_max_tmp, recip_max_tmp >> tmp_shift
+        .set recip_mask_shift, recip_mask_shift + tmp_shift
+    .endif
+    .set tmp_shift, tmp_shift >> 1
+.endr
+.if recip_max_tmp
+    .set recip_mask_shift, recip_mask_shift + 1
+.endif
+.set recip_mask_shift, (recip_mask_shift + 1) & 62
+.set recip_max, recip_max & (255 << recip_mask_shift)
+//.set recip_max, 2
 #endif
 
 udiv32_arm: