Take 2 at 'Consolidate all fixed point math routines in one library' (FS#10400) by Jeffrey Goode

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@21664 a1c6a512-1295-4272-9138-f99709370657

1 files changed, 93 insertions, 0 deletions

diff --git a/apps/fracmul.h b/apps/fracmul.h
new file mode 100644
index 0000000000..5cc83af624
--- /dev/null
+++ b/apps/fracmul.h
@@ -0,0 +1,93 @@
+#ifndef _FRACMUL_H
+#define _FRACMUL_H
+
+/** FRACTIONAL MULTIPLICATION - TAKEN FROM apps/dsp.h
+ *  Multiply two fixed point numbers with 31 fractional bits:
+ *      FRACMUL(x, y)
+ *
+ *  Multiply two fixed point numbers with 31 fractional bits,
+ *          then shift left by z bits:
+ *      FRACMUL_SHL(x, y, z)
+ *          NOTE: z must be in the range 1-8 on Coldfire targets.
+ */
+
+
+/* A bunch of fixed point assembler helper macros */
+#if defined(CPU_COLDFIRE)
+/* These macros use the Coldfire EMAC extension and need the MACSR flags set
+ * to fractional mode with no rounding.
+ */
+
+/* Multiply two S.31 fractional integers and return the sign bit and the
+ * 31 most significant bits of the result.
+ */
+#define FRACMUL(x, y) \
+({ \
+    long t; \
+    asm ("mac.l    %[a], %[b], %%acc0\n\t" \
+         "movclr.l %%acc0, %[t]\n\t" \
+         : [t] "=r" (t) : [a] "r" (x), [b] "r" (y)); \
+    t; \
+})
+
+/* Multiply two S.31 fractional integers, and return the 32 most significant
+ * bits after a shift left by the constant z. NOTE: Only works for shifts of
+ * 1 to 8 on Coldfire!
+ */
+#define FRACMUL_SHL(x, y, z) \
+({ \
+    long t, t2; \
+    asm ("mac.l    %[a], %[b], %%acc0\n\t" \
+         "moveq.l  %[d], %[t]\n\t" \
+         "move.l   %%accext01, %[t2]\n\t" \
+         "and.l    %[mask], %[t2]\n\t" \
+         "lsr.l    %[t], %[t2]\n\t" \
+         "movclr.l %%acc0, %[t]\n\t" \
+         "asl.l    %[c], %[t]\n\t" \
+         "or.l     %[t2], %[t]\n\t" \
+         : [t] "=&d" (t), [t2] "=&d" (t2) \
+         : [a] "r" (x), [b] "r" (y), [mask] "d" (0xff), \
+           [c] "i" ((z)), [d] "i" (8 - (z))); \
+    t; \
+})
+
+#elif defined(CPU_ARM)
+
+/* Multiply two S.31 fractional integers and return the sign bit and the
+ * 31 most significant bits of the result.
+ */
+#define FRACMUL(x, y) \
+({ \
+    long t, t2; \
+    asm ("smull    %[t], %[t2], %[a], %[b]\n\t" \
+         "mov      %[t2], %[t2], asl #1\n\t" \
+         "orr      %[t], %[t2], %[t], lsr #31\n\t" \
+         : [t] "=&r" (t), [t2] "=&r" (t2) \
+         : [a] "r" (x), [b] "r" (y)); \
+    t; \
+})
+
+/* Multiply two S.31 fractional integers, and return the 32 most significant
+ * bits after a shift left by the constant z.
+ */
+#define FRACMUL_SHL(x, y, z) \
+({ \
+    long t, t2; \
+    asm ("smull    %[t], %[t2], %[a], %[b]\n\t" \
+         "mov      %[t2], %[t2], asl %[c]\n\t" \
+         "orr      %[t], %[t2], %[t], lsr %[d]\n\t" \
+         : [t] "=&r" (t), [t2] "=&r" (t2) \
+         : [a] "r" (x), [b] "r" (y), \
+           [c] "M" ((z) + 1), [d] "M" (31 - (z))); \
+    t; \
+})
+
+#else
+
+#define FRACMUL(x, y) (long) (((((long long) (x)) * ((long long) (y))) >> 31))
+#define FRACMUL_SHL(x, y, z) \
+((long)(((((long long) (x)) * ((long long) (y))) >> (31 - (z)))))
+
+#endif
+
+#endif