sw/device/lib/base/internal/status.h

// Copyright lowRISC contributors.
// Licensed under the Apache License, Version 2.0, see LICENSE for details.
// SPDX-License-Identifier: Apache-2.0

#ifndef OPENTITAN_SW_DEVICE_LIB_BASE_INTERNAL_STATUS_H_
#define OPENTITAN_SW_DEVICE_LIB_BASE_INTERNAL_STATUS_H_

#ifndef USING_INTERNAL_STATUS
#error "Do not include internal/status.h directly. Include status.h instead."
#endif
#include "sw/device/lib/base/bitfield.h"

#define USING_ABSL_STATUS
#include "sw/device/lib/base/internal/absl_status.h"
#undef USING_ABSL_STATUS
#ifdef __cplusplus
extern "C" {
#endif

/**
 * We use the error category codes from absl_status.h.  We build a packed
 * status value that identifies the source of the error (in the form of the
 * module identifier and line number).
 *
 * By default, the module identifier is the first three letters of the
 * source filename.  The identifier can be overridden (per-module) with the
 * DECLARE_MODULE_ID macro.
 *
 * Our status codes are arranged as a packed bitfield, with the sign
 * bit signifying whether the value represents a result or an error.
 *
 * All Ok (good) values:
 *     31                                             0
 *  +---+---------------------------------------------+
 *  |   |                  31 bit                     |
 *  | 0 |                  Result                     |
 *  +---+---------------------------------------------+
 *
 * All Error values:
 *     31      26      21      16             5       0
 *  +---+-------+-------+-------+-------------+-------+
 *  |   |   15 bit              | 11 bit      | 5 bit |
 *  | 1 |   Module Identifier   | Line Number | code  |
 *  +---+-------+-------+-------+-------------+-------+
 *
 * The module identifier value is interpreted as three 5-bit fields
 * representing the characters [0x40..0x5F] (e.g. [@ABC ... _]).
 */

#define STATUS_FIELD_CODE ((bitfield_field32_t){.mask = 0x1f, .index = 0})
#define STATUS_FIELD_ARG ((bitfield_field32_t){.mask = 0x7ff, .index = 5})
#define STATUS_FIELD_MODULE_ID \
  ((bitfield_field32_t){.mask = 0x7fff, .index = 16})
#define STATUS_BIT_ERROR 31

// clang-format off
#define ASCII_5BIT(v) ( \
    /*uppercase characters*/  (v) >= '@' && (v) <= '_' ? (v) - '@' \
    /*lower cvt upper*/     : (v) >= '`' && (v) <= 'z' ? (v) - '`' \
    /*else cvt underscore*/ : '_' - '@'                            \
  )
// clang-format on

/*
 * Creates a module ID from 3 ASCII characters.
 *
 * Note: the result is pre-shifted into the module identifier position within
 * a `status_t`.
 * - The kStatusModuleId can simply be ORed in when constucting a `status_t`.
 * - The value of MAKE_MODULE_ID can be used in constructing constants for
 *   types compatible with `status_t`.
 *
 * To declare a module-id in one of your own files:
 * #define MODULE_ID MAKE_MODULE_ID('a', 'b', 'c')
 */
#define MAKE_MODULE_ID(a, b, c) \
  (ASCII_5BIT(a) << 16) | (ASCII_5BIT(b) << 21) | (ASCII_5BIT(c) << 26)

#ifdef __cplusplus
}
#endif
#endif  // OPENTITAN_SW_DEVICE_LIB_BASE_INTERNAL_STATUS_H_