| 1 | /* -*- c++ -*- */
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| 2 | /*-----------------------------------------------------------------------------
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| 3 | * Delay routines
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| 4 | *-----------------------------------------------------------------------------
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| 5 | * Code taken from USRP2 firmware (GNU Radio Project), version 3.0.2,
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| 6 | * Copyright 2003 Free Software Foundation, Inc.
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| 7 | *-----------------------------------------------------------------------------
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| 8 | * This code is part of usbjtag. usbjtag is free software; you can redistribute
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| 9 | * it and/or modify it under the terms of the GNU General Public License as
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| 10 | * published by the Free Software Foundation; either version 2 of the License,
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| 11 | * or (at your option) any later version. usbjtag is distributed in the hope
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| 12 | * that it will be useful, but WITHOUT ANY WARRANTY; without even the implied
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| 13 | * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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| 14 | * GNU General Public License for more details. You should have received a
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| 15 | * copy of the GNU General Public License along with this program in the file
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| 16 | * COPYING; if not, write to the Free Software Foundation, Inc., 51 Franklin
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| 17 | * St, Fifth Floor, Boston, MA 02110-1301 USA
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| 18 | *-----------------------------------------------------------------------------
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| 19 | */
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| 20 |
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| 21 | /*
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| 22 | * Delay approximately 1 microsecond (including overhead in udelay).
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| 23 | */
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| 24 | static void
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| 25 | udelay1 (void) _naked
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| 26 | {
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| 27 | _asm ; lcall that got us here took 4 bus cycles
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| 28 | ret ; 4 bus cycles
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| 29 | _endasm;
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| 30 | }
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| 31 |
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| 32 | /*
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| 33 | * delay for approximately usecs microseconds
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| 34 | */
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| 35 | void
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| 36 | udelay (unsigned char usecs)
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| 37 | {
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| 38 | do {
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| 39 | udelay1 ();
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| 40 | } while (--usecs != 0);
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| 41 | }
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| 42 |
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| 43 |
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| 44 | /*
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| 45 | * Delay approximately 1 millisecond.
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| 46 | * We're running at 48 MHz, so we need 48,000 clock cycles.
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| 47 | *
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| 48 | * Note however, that each bus cycle takes 4 clock cycles (not obvious,
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| 49 | * but explains the factor of 4 problem below).
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| 50 | */
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| 51 | static void
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| 52 | mdelay1 (void) _naked
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| 53 | {
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| 54 | _asm
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| 55 | mov dptr,#(-1200 & 0xffff)
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| 56 | 002$:
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| 57 | inc dptr ; 3 bus cycles
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| 58 | mov a, dpl ; 2 bus cycles
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| 59 | orl a, dph ; 2 bus cycles
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| 60 | jnz 002$ ; 3 bus cycles
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| 61 |
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| 62 | ret
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| 63 | _endasm;
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| 64 | }
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| 65 |
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| 66 | void
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| 67 | mdelay (unsigned int msecs)
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| 68 | {
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| 69 | do {
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| 70 | mdelay1 ();
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| 71 | } while (--msecs != 0);
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| 72 | }
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| 73 |
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| 74 |
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