diff options
Diffstat (limited to 'src/include')
| -rw-r--r-- | src/include/base3.h | 48 | ||||
| -rw-r--r-- | src/include/gpio.h | 14 |
2 files changed, 53 insertions, 9 deletions
diff --git a/src/include/base3.h b/src/include/base3.h new file mode 100644 index 0000000000..e92cc8bae7 --- /dev/null +++ b/src/include/base3.h @@ -0,0 +1,48 @@ +/* + * This file is part of the coreboot project. + * + * Copyright 2014 Google Inc. + * + * 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; version 2 of the License. + * + * 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., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA + */ + +#ifndef __SRC_INCLUDE_BASE3_H__ +#define __SRC_INCLUDE_BASE3_H__ + +/* We translate a floating pin (Z) as the ternary digit 2. */ +#define Z 2 + +/* + * This provides a variadic macro BASE3() that can be used to translate a set of + * pin states into its base-3 integer representation, even in the context of a + * static initializer. You can call it with any number of up to 6 arguments, + * e.g. BASE3(1, Z) -> 5 or BASE3(0, Z, 1, 0) -> 21. Just don't look too closely + * at how the sausage is made. (Pay extra attention to typos when expanding it!) + */ +#define _BASE3_IMPL_1(arg0, arg1, arg2, arg3, arg4, arg5) arg0 +#define _BASE3_IMPL_2(arg0, arg1, arg2, arg3, arg4, arg5) \ + (arg1 + (3 * _BASE3_IMPL_1(arg0, arg1, arg2, arg3, arg4, arg5))) +#define _BASE3_IMPL_3(arg0, arg1, arg2, arg3, arg4, arg5) \ + (arg2 + (3 * _BASE3_IMPL_2(arg0, arg1, arg2, arg3, arg4, arg5))) +#define _BASE3_IMPL_4(arg0, arg1, arg2, arg3, arg4, arg5) \ + (arg3 + (3 * _BASE3_IMPL_3(arg0, arg1, arg2, arg3, arg4, arg5))) +#define _BASE3_IMPL_5(arg0, arg1, arg2, arg3, arg4, arg5) \ + (arg4 + (3 * _BASE3_IMPL_4(arg0, arg1, arg2, arg3, arg4, arg5))) +#define _BASE3_IMPL_6(arg0, arg1, arg2, arg3, arg4, arg5) \ + (arg5 + (3 * _BASE3_IMPL_5(arg0, arg1, arg2, arg3, arg4, arg5))) +#define _BASE3_IMPL(arg0, arg1, arg2, arg3, arg4, arg5, NARGS, ...) \ + _BASE3_IMPL##NARGS(arg0, arg1, arg2, arg3, arg4, arg5) +#define BASE3(...) _BASE3_IMPL(__VA_ARGS__, _6, _5, _4, _3, _2, _1) + +#endif /* __SRC_INCLUDE_BASE3_H__ */ diff --git a/src/include/gpio.h b/src/include/gpio.h index af06697050..b2a341dabc 100644 --- a/src/include/gpio.h +++ b/src/include/gpio.h @@ -36,17 +36,13 @@ void gpio_output(gpio_t gpio, int value); /* * Read the value presented by the set of GPIOs, when each pin is interpreted - * as a number in 0..2 range depending on the external pullup situation. + * as a base-3 digit (LOW = 0, HIGH = 1, Z/floating = 2). + * Example: X1 = Z, X2 = 1 -> gpio_get_tristates({GPIO(X1), GPIO(X2)}) = 5 + * BASE3() from <base3.h> can generate numbers to compare the result to. * - * Depending on the third parameter, the return value is either a set of two - * bit fields, each representing one GPIO value, or a number where each GPIO is - * included multiplied by 3^gpio_num, resulting in a true tertiary value. - * - * gpio[]: pin positions to read. little-endian (less significant value first). + * gpio[]: pin positions to read. gpio[0] is less significant than gpio[1]. * num_gpio: number of pins to read. - * tertiary: 1: pins are interpreted as a quad coded tertiary. - * 0: pins are interpreted as a set of two bit fields. */ -int gpio_get_tristates(gpio_t gpio[], int num_gpio, int tertiary); +int gpio_get_tristates(gpio_t gpio[], int num_gpio); #endif /* __SRC_INCLUDE_GPIO_H__ */ |