diff options
| -rw-r--r-- | drivers/media/dvb/frontends/stb0899_algo.c | 69 |
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 2d2b87cf6d0..f1432cb2926 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); |