paul@113 | 1 | /* |
paul@113 | 2 | * Some simple utility functions. |
paul@113 | 3 | * |
paul@113 | 4 | * Copyright (C) 2018 Paul Boddie <paul@boddie.org.uk> |
paul@113 | 5 | * |
paul@113 | 6 | * This program is free software: you can redistribute it and/or modify |
paul@113 | 7 | * it under the terms of the GNU General Public License as published by |
paul@113 | 8 | * the Free Software Foundation, either version 3 of the License, or |
paul@113 | 9 | * (at your option) any later version. |
paul@113 | 10 | * |
paul@113 | 11 | * This program is distributed in the hope that it will be useful, |
paul@113 | 12 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
paul@113 | 13 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
paul@113 | 14 | * GNU General Public License for more details. |
paul@113 | 15 | * |
paul@113 | 16 | * You should have received a copy of the GNU General Public License |
paul@113 | 17 | * along with this program. If not, see <http://www.gnu.org/licenses/>. |
paul@113 | 18 | */ |
paul@113 | 19 | |
paul@113 | 20 | #include "utils.h" |
paul@113 | 21 | |
paul@113 | 22 | |
paul@113 | 23 | |
paul@113 | 24 | /* A simple busy wait involving a register-based counter. */ |
paul@113 | 25 | |
paul@113 | 26 | void wait(uint32_t delay) |
paul@113 | 27 | { |
paul@113 | 28 | uint32_t counter = delay; |
paul@113 | 29 | |
paul@113 | 30 | if (!delay) return; |
paul@113 | 31 | while (counter--) __asm__(""); /* retain loop */ |
paul@113 | 32 | } |
paul@113 | 33 | |
paul@113 | 34 | /* Wrap a pointer within the given limits. */ |
paul@113 | 35 | |
paul@113 | 36 | uint8_t *wrap_pointer(uint8_t *ptr, uint8_t *lower, uint8_t *upper) |
paul@113 | 37 | { |
paul@113 | 38 | uint32_t size = upper - lower; |
paul@113 | 39 | |
paul@113 | 40 | if (ptr < lower) |
paul@113 | 41 | return upper - (lower - ptr) % size; |
paul@113 | 42 | else if (ptr >= upper) |
paul@113 | 43 | return lower + (ptr - upper) % size; |
paul@113 | 44 | else |
paul@113 | 45 | return ptr; |
paul@113 | 46 | } |
paul@113 | 47 | |
paul@113 | 48 | /* Wrap a value within the bounds [0, limit). */ |
paul@113 | 49 | |
paul@113 | 50 | int wrap_value(int value, int limit) |
paul@113 | 51 | { |
paul@113 | 52 | if (value < 0) |
paul@113 | 53 | return limit - (-value % limit); |
paul@113 | 54 | else if (value >= limit) |
paul@113 | 55 | return (value - limit) % limit; |
paul@113 | 56 | else |
paul@113 | 57 | return value; |
paul@113 | 58 | } |