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authorReinhard Nissl <rnissl@gmx.de>2008-01-21 22:43:18 +0300
committerMauro Carvalho Chehab <mchehab@redhat.com>2008-12-29 22:53:21 +0300
commit27713c8ba45e807c64c53a8a865adbe3a73f3b2d (patch)
tree95e2dd39fcd800f3c842ff93de511be1906148e1 /drivers/media/dvb/frontends/stb0899_algo.c
parent561374113e6dbd717ac4a578d99834219de9d3c1 (diff)
downloadlinux-27713c8ba45e807c64c53a8a865adbe3a73f3b2d.tar.xz
V4L/DVB (9449): Code Simplification: use do_div() instead
Signed-off-by: Reinhard Nissl <rnissl@gmx.de> Signed-off-by: Manu Abraham <manu@linuxtv.org> Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Diffstat (limited to 'drivers/media/dvb/frontends/stb0899_algo.c')
-rw-r--r--drivers/media/dvb/frontends/stb0899_algo.c69
1 files changed, 34 insertions, 35 deletions
diff --git a/drivers/media/dvb/frontends/stb0899_algo.c b/drivers/media/dvb/frontends/stb0899_algo.c
index 2d2b87cf6d00..f1432cb29262 100644
--- a/drivers/media/dvb/frontends/stb0899_algo.c
+++ b/drivers/media/dvb/frontends/stb0899_algo.c
@@ -23,27 +23,12 @@
#include "stb0899_priv.h"
#include "stb0899_reg.h"
-/*
- * BinaryFloatDiv
- * float division with integer
- */
-static long BinaryFloatDiv(long n1, long n2, int precision)
+inline u32 stb0899_do_div(u64 n, u32 d)
{
- int i = 0;
- long result = 0;
+ /* wrap do_div() for ease of use */
- while (i <= precision) {
- if (n1 < n2) {
- result *= 2;
- n1 *= 2;
- } else {
- result = result * 2 + 1;
- n1 = (n1 - n2) * 2;
- }
- i++;
- }
-
- return result;
+ do_div(n, d);
+ return n;
}
/*
@@ -52,15 +37,15 @@ static long BinaryFloatDiv(long n1, long n2, int precision)
*/
static u32 stb0899_calc_srate(u32 master_clk, u8 *sfr)
{
- u32 tmp, tmp2, mclk;
+ u64 tmp;
- mclk = master_clk / 4096L; /* MasterClock * 10 / 2^20 */
- tmp = (((u32) sfr[0] << 12) + ((u32) sfr[1] << 4)) / 16;
+ /* srate = (SFR * master_clk) >> 20 */
- tmp *= mclk;
- tmp /= 16;
- tmp2 = ((u32) sfr[2] * mclk) / 256;
- tmp += tmp2;
+ /* sfr is of size 20 bit, stored with an offset of 4 bit */
+ tmp = (((u32)sfr[0]) << 16) | (((u32)sfr[1]) << 8) | sfr[2];
+ tmp &= ~0xf;
+ tmp *= master_clk;
+ tmp >>= 24;
return tmp;
}
@@ -72,7 +57,7 @@ static u32 stb0899_calc_srate(u32 master_clk, u8 *sfr)
u32 stb0899_get_srate(struct stb0899_state *state)
{
struct stb0899_internal *internal = &state->internal;
- u8 sfr[4];
+ u8 sfr[3];
stb0899_read_regs(state, STB0899_SFRH, sfr, 3);
@@ -101,16 +86,30 @@ static u32 stb0899_set_srate(struct stb0899_state *state, u32 master_clk, u32 sr
*/
// srate_up += (srate_up * 3) / 100;
- tmp = BinaryFloatDiv(srate, master_clk, 20);
-// tmp_up = BinaryFloatDiv(srate_up, master_clk, 20);
+ /*
+ * srate = (SFR * master_clk) >> 20
+ * <=>
+ * SFR = srate << 20 / master_clk
+ *
+ * rounded:
+ * SFR = (srate << 21 + master_clk) / (2 * master_clk)
+ *
+ * stored as 20 bit number with an offset of 4 bit:
+ * sfr = SFR << 4;
+ */
+// tmp_up = stb0899_do_div((((u64)srate_up) << 21) + master_clk, 2 * master_clk);
+// tmp_up <<= 4;
+
+ tmp = stb0899_do_div((((u64)srate) << 21) + master_clk, 2 * master_clk);
+ tmp <<= 4;
-// sfr_up[0] = (tmp_up >> 12) & 0xff;
-// sfr_up[1] = (tmp_up >> 4) & 0xff;
-// sfr_up[2] = tmp_up & 0x0f;
+// sfr_up[0] = tmp_up >> 16;
+// sfr_up[1] = tmp_up >> 8;
+// sfr_up[2] = tmp_up;
- sfr[0] = (tmp >> 12) & 0xff;
- sfr[1] = (tmp >> 4) & 0xff;
- sfr[2] = (tmp << 4) & 0xf0;
+ sfr[0] = tmp >> 16;
+ sfr[1] = tmp >> 8;
+ sfr[2] = tmp;
// stb0899_write_regs(state, STB0899_SFRUPH, sfr_up, 3);
stb0899_write_regs(state, STB0899_SFRH, sfr, 3);