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V4L/DVB (9449): Code Simplification: use do_div() instead

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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>
This commit is contained in:
Reinhard Nissl 2008-01-21 16:43:18 -03:00 committed by Mauro Carvalho Chehab
parent 561374113e
commit 27713c8ba4
1 changed files with 34 additions and 35 deletions
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69
drivers/media/dvb/frontends/stb0899_algo.c
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@ -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;
// sfr_up[0] = (tmp_up >> 12) & 0xff;
// sfr_up[1] = (tmp_up >> 4) & 0xff;
// sfr_up[2] = tmp_up & 0x0f;
tmp = stb0899_do_div((((u64)srate) << 21) + master_clk, 2 * master_clk);
tmp <<= 4;
sfr[0] = (tmp >> 12) & 0xff;
sfr[1] = (tmp >> 4) & 0xff;
sfr[2] = (tmp << 4) & 0xf0;
// sfr_up[0] = tmp_up >> 16;
// sfr_up[1] = tmp_up >> 8;
// sfr_up[2] = tmp_up;
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);