diff options
Diffstat (limited to 'src/smi_dac.c')
| -rw-r--r-- | src/smi_dac.c | 99 |
1 files changed, 99 insertions, 0 deletions
diff --git a/src/smi_dac.c b/src/smi_dac.c new file mode 100644 index 0000000..627b892 --- /dev/null +++ b/src/smi_dac.c @@ -0,0 +1,99 @@ +/* Header: //Mercury/Projects/archives/XFree86/4.0/smi_dac.c-arc 1.8 27 Nov 2000 15:47:08 Frido $ */ + +/* +Copyright (C) 1994-1998 The XFree86 Project, Inc. All Rights Reserved. +Copyright (C) 2000 Silicon Motion, Inc. All Rights Reserved. + +Permission is hereby granted, free of charge, to any person obtaining a copy of +this software and associated documentation files (the "Software"), to deal in +the Software without restriction, including without limitation the rights to +use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies +of the Software, and to permit persons to whom the Software is furnished to do +so, subject to the following conditions: + +The above copyright notice and this permission notice shall be included in all +copies or substantial portions of the Software. + +THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR +IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FIT- +NESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE +XFREE86 PROJECT BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN +AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION +WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. + +Except as contained in this notice, the names of the XFree86 Project and +Silicon Motion shall not be used in advertising or otherwise to promote the +sale, use or other dealings in this Software without prior written +authorization from the XFree86 Project and Silicon Motion. +*/ +/* $XFree86: xc/programs/Xserver/hw/xfree86/drivers/siliconmotion/smi_dac.c,v 1.2 2001/11/30 12:11:59 eich Exp $ */ + +#include "smi.h" + +#define BASE_FREQ 14.31818 /* MHz */ + +void +SMI_CommonCalcClock(int scrnIndex, long freq, int min_m, int min_n1, + int max_n1, int min_n2, int max_n2, long freq_min, + long freq_max, unsigned char *mdiv, unsigned char *ndiv) +{ + double div, diff, best_diff; + unsigned int m; + unsigned char n1, n2; + unsigned char best_n1 = 63, best_n2 = 3, best_m = 255; + + double ffreq = freq / 1000.0 / BASE_FREQ; + double ffreq_min = freq_min / 1000.0 / BASE_FREQ; + double ffreq_max = freq_max / 1000.0 / BASE_FREQ; + + if (ffreq < ffreq_min / (1 << max_n2)) + { + xf86DrvMsg(scrnIndex,X_WARNING,"invalid frequency %1.3f MHz [freq >= %1.3f MHz]\n", + ffreq * BASE_FREQ, ffreq_min * BASE_FREQ / (1 << max_n2)); + ffreq = ffreq_min / (1 << max_n2); + } + if (ffreq > ffreq_max / (1 << min_n2)) + { + xf86DrvMsg(scrnIndex,X_WARNING,"invalid frequency %1.3f MHz [freq <= %1.3f MHz]\n", + ffreq * BASE_FREQ, ffreq_max * BASE_FREQ / (1 << min_n2)); + ffreq = ffreq_max / (1 << min_n2); + } + + /* work out suitable timings */ + best_diff = ffreq; + + for (n2 = min_n2; n2 <= max_n2; n2++) + { + for (n1 = min_n1; n1 <= max_n1; n1++) + { + m = (int)(ffreq * n1 * (1 << n2) + 0.5); + if ( (m < min_m) || (m > 255) ) + { + continue; + } + div = (double)(m) / (double)(n1); + if ( (div >= ffreq_min) && (div <= ffreq_max) ) + { + diff = ffreq - div / (1 << n2); + if (diff < 0.0) + { + diff = -diff; + } + if (diff < best_diff) + { + best_diff = diff; + best_m = m; + best_n1 = n1; + best_n2 = n2; + } + } + } + } + + DEBUG((VERBLEV, "Clock parameters for %1.6f MHz: m=%d, n1=%d, n2=%d\n", + ((double)(best_m) / (double)(best_n1) / (1 << best_n2)) * BASE_FREQ, + best_m, best_n1, best_n2)); + + *ndiv = best_n1 | (best_n2 << 6); + *mdiv = best_m; +} |