From eba47ff3679443feadeee17aad7c8478ec71eec2 Mon Sep 17 00:00:00 2001 From: David Schleef Date: Mon, 6 Mar 2000 01:18:53 +0000 Subject: [PATCH] New file --- comedi/drivers/8253.h | 113 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 113 insertions(+) create mode 100644 comedi/drivers/8253.h diff --git a/comedi/drivers/8253.h b/comedi/drivers/8253.h new file mode 100644 index 00000000..cc6a3f8d --- /dev/null +++ b/comedi/drivers/8253.h @@ -0,0 +1,113 @@ +/* + comedi/drivers/8253.h + Header file for 8253 + + COMEDI - Linux Control and Measurement Device Interface + Copyright (C) 2000 David A. Schleef + + This program is free software; you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation; either version 2 of the License, or + (at your option) any later version. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program; if not, write to the Free Software + Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. + +*/ + +#ifndef _8253_H +#define _8253_H + +extern int i8253_osc_base; + +#define i8253_cascade_ns_to_timer i8253_cascade_ns_to_timer_power + +static inline void i8253_cascade_ns_to_timer_2div(int *d1, int *d2, int *nanosec, int round_mode) +{ + int divider; + int div1, div2; + int div1_glb, div2_glb, ns_glb; + int div1_lub, div2_lub, ns_lub; + int ns; + + divider = (*nanosec + i8253_osc_base / 2) / i8253_osc_base; + + /* find 2 integers 1<={x,y}<=65536 such that x*y is + close to divider */ + + div1_lub = div2_lub = 0; + div1_glb = div2_glb = 0; + + ns_glb = 0; + ns_lub = 0xffffffff; + + div2 = 0x10000; + for (div1 = divider / 65536 + 1; div1 < div2; div1++) { + div2 = divider / div1; + + ns = i8253_osc_base * div1 * div2; + if (ns <= *nanosec && ns > ns_glb) { + ns_glb = ns; + div1_glb = div1; + div2_glb = div2; + } + + div2++; + if (div2 <= 65536) { + ns = i8253_osc_base * div1 * div2; + if (ns > *nanosec && ns < ns_lub) { + ns_lub = ns; + div1_lub = div1; + div2_lub = div2; + } + } + } + + *d1 = div1_lub; + *d2 = div2_lub; +} + +static inline void i8253_cascade_ns_to_timer_power(int *d1, int *d2, int *nanosec, int round_mode) +{ + int div1, div2; + int base; + + for (div1 = 1; div1 <= (1 << 16); div1 <<= 1) { + base = i8253_osc_base * div1; + switch (round_mode) { + case TRIG_ROUND_NEAREST: + default: + div2 = (*nanosec + base / 2) / base; + break; + case TRIG_ROUND_DOWN: + div2 = (*nanosec) / base; + break; + case TRIG_ROUND_UP: + div2 = (*nanosec + base - 1) / base; + break; + } + if (div2 <= 65536) { + *nanosec = div2 * base; + *d1 = div1 & 0xffff; + *d2 = div2 & 0xffff; + return; + } + } + + /* shouldn't get here */ + div1 = 0x10000; + div2 = 0x10000; + *nanosec = div1 * div2 * i8253_osc_base; + *d1 = div1 & 0xffff; + *d2 = div2 & 0xffff; +} + + +#endif + -- 2.26.2