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+/*
+ * Copyright (c) 2016-2020, Yann Collet, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under both the BSD-style license (found in the
+ * LICENSE file in the root directory of this source tree) and the GPLv2 (found
+ * in the COPYING file in the root directory of this source tree).
+ * You may select, at your option, one of the above-listed licenses.
+ */
+
+
+/* benchfn :
+ * benchmark any function on a set of input
+ * providing result in nanoSecPerRun
+ * or detecting and returning an error
+ */
+
+#if defined (__cplusplus)
+extern "C" {
+#endif
+
+#ifndef BENCH_FN_H_23876
+#define BENCH_FN_H_23876
+
+/* ===  Dependencies  === */
+#include <stddef.h>   /* size_t */
+
+
+/* ====  Benchmark any function, iterated on a set of blocks  ==== */
+
+/* BMK_runTime_t: valid result return type */
+
+typedef struct {
+    double nanoSecPerRun;  /* time per iteration (over all blocks) */
+    size_t sumOfReturn;         /* sum of return values */
+} BMK_runTime_t;
+
+
+/* BMK_runOutcome_t:
+ * type expressing the outcome of a benchmark run by BMK_benchFunction(),
+ * which can be either valid or invalid.
+ * benchmark outcome can be invalid if errorFn is provided.
+ * BMK_runOutcome_t must be considered "opaque" : never access its members directly.
+ * Instead, use its assigned methods :
+ * BMK_isSuccessful_runOutcome, BMK_extract_runTime, BMK_extract_errorResult.
+ * The structure is only described here to allow its allocation on stack. */
+
+typedef struct {
+    BMK_runTime_t internal_never_ever_use_directly;
+    size_t error_result_never_ever_use_directly;
+    int error_tag_never_ever_use_directly;
+} BMK_runOutcome_t;
+
+
+/* prototypes for benchmarked functions */
+typedef size_t (*BMK_benchFn_t)(const void* src, size_t srcSize, void* dst, size_t dstCapacity, void* customPayload);
+typedef size_t (*BMK_initFn_t)(void* initPayload);
+typedef unsigned (*BMK_errorFn_t)(size_t);
+
+
+/* BMK_benchFunction() parameters are provided via the following structure.
+ * A structure is preferable for readability,
+ * as the number of parameters required is fairly large.
+ * No initializer is provided, because it doesn't make sense to provide some "default" :
+ * all parameters must be specified by the caller.
+ * optional parameters are labelled explicitly, and accept value NULL when not used */
+typedef struct {
+    BMK_benchFn_t benchFn;    /* the function to benchmark, over the set of blocks */
+    void* benchPayload;       /* pass custom parameters to benchFn  :
+                               * (*benchFn)(srcBuffers[i], srcSizes[i], dstBuffers[i], dstCapacities[i], benchPayload) */
+    BMK_initFn_t initFn;      /* (*initFn)(initPayload) is run once per run, at the beginning. */
+    void* initPayload;        /* Both arguments can be NULL, in which case nothing is run. */
+    BMK_errorFn_t errorFn;    /* errorFn will check each return value of benchFn over each block, to determine if it failed or not.
+                               * errorFn can be NULL, in which case no check is performed.
+                               * errorFn must return 0 when benchFn was successful, and >= 1 if it detects an error.
+                               * Execution is stopped as soon as an error is detected.
+                               * the triggering return value can be retrieved using BMK_extract_errorResult(). */
+    size_t blockCount;        /* number of blocks to operate benchFn on.
+                               * It's also the size of all array parameters :
+                               * srcBuffers, srcSizes, dstBuffers, dstCapacities, blockResults */
+    const void *const * srcBuffers; /* read-only array of buffers to be operated on by benchFn */
+    const size_t* srcSizes;   /* read-only array containing sizes of srcBuffers */
+    void *const * dstBuffers; /* array of buffers to be written into by benchFn. This array is not optional, it must be provided even if unused by benchfn. */
+    const size_t* dstCapacities; /* read-only array containing capacities of dstBuffers. This array must be present. */
+    size_t* blockResults;     /* Optional: store the return value of benchFn for each block. Use NULL if this result is not requested. */
+} BMK_benchParams_t;
+
+
+/* BMK_benchFunction() :
+ * This function benchmarks benchFn and initFn, providing a result.
+ *
+ * params : see description of BMK_benchParams_t above.
+ * nbLoops: defines number of times benchFn is run over the full set of blocks.
+ *          Minimum value is 1. A 0 is interpreted as a 1.
+ *
+ * @return: can express either an error or a successful result.
+ *          Use BMK_isSuccessful_runOutcome() to check if benchmark was successful.
+ *          If yes, extract the result with BMK_extract_runTime(),
+ *          it will contain :
+ *              .sumOfReturn : the sum of all return values of benchFn through all of blocks
+ *              .nanoSecPerRun : time per run of benchFn + (time for initFn / nbLoops)
+ *          .sumOfReturn is generally intended for functions which return a # of bytes written into dstBuffer,
+ *              in which case, this value will be the total amount of bytes written into dstBuffer.
+ *
+ * blockResults : when provided (!= NULL), and when benchmark is successful,
+ *                params.blockResults contains all return values of `benchFn` over all blocks.
+ *                when provided (!= NULL), and when benchmark failed,
+ *                params.blockResults contains return values of `benchFn` over all blocks preceding and including the failed block.
+ */
+BMK_runOutcome_t BMK_benchFunction(BMK_benchParams_t params, unsigned nbLoops);
+
+
+
+/* check first if the benchmark was successful or not */
+int BMK_isSuccessful_runOutcome(BMK_runOutcome_t outcome);
+
+/* If the benchmark was successful, extract the result.
+ * note : this function will abort() program execution if benchmark failed !
+ *        always check if benchmark was successful first !
+ */
+BMK_runTime_t BMK_extract_runTime(BMK_runOutcome_t outcome);
+
+/* when benchmark failed, it means one invocation of `benchFn` failed.
+ * The failure was detected by `errorFn`, operating on return values of `benchFn`.
+ * Returns the faulty return value.
+ * note : this function will abort() program execution if benchmark did not failed.
+ *        always check if benchmark failed first !
+ */
+size_t BMK_extract_errorResult(BMK_runOutcome_t outcome);
+
+
+
+/* ====  Benchmark any function, returning intermediate results  ==== */
+
+/* state information tracking benchmark session */
+typedef struct BMK_timedFnState_s BMK_timedFnState_t;
+
+/* BMK_benchTimedFn() :
+ * Similar to BMK_benchFunction(), most arguments being identical.
+ * Automatically determines `nbLoops` so that each result is regularly produced at interval of about run_ms.
+ * Note : minimum `nbLoops` is 1, therefore a run may last more than run_ms, and possibly even more than total_ms.
+ * Usage - initialize timedFnState, select benchmark duration (total_ms) and each measurement duration (run_ms)
+ *         call BMK_benchTimedFn() repetitively, each measurement is supposed to last about run_ms
+ *         Check if total time budget is spent or exceeded, using BMK_isCompleted_TimedFn()
+ */
+BMK_runOutcome_t BMK_benchTimedFn(BMK_timedFnState_t* timedFnState,
+                                  BMK_benchParams_t params);
+
+/* Tells if duration of all benchmark runs has exceeded total_ms
+ */
+int BMK_isCompleted_TimedFn(const BMK_timedFnState_t* timedFnState);
+
+/* BMK_createTimedFnState() and BMK_resetTimedFnState() :
+ * Create/Set BMK_timedFnState_t for next benchmark session,
+ * which shall last a minimum of total_ms milliseconds,
+ * producing intermediate results, paced at interval of (approximately) run_ms.
+ */
+BMK_timedFnState_t* BMK_createTimedFnState(unsigned total_ms, unsigned run_ms);
+void BMK_resetTimedFnState(BMK_timedFnState_t* timedFnState, unsigned total_ms, unsigned run_ms);
+void BMK_freeTimedFnState(BMK_timedFnState_t* state);
+
+
+/* BMK_timedFnState_shell and BMK_initStatic_timedFnState() :
+ * Makes it possible to statically allocate a BMK_timedFnState_t on stack.
+ * BMK_timedFnState_shell is only there to allocate space,
+ * never ever access its members.
+ * BMK_timedFnState_t() actually accepts any buffer.
+ * It will check if provided buffer is large enough and is correctly aligned,
+ * and will return NULL if conditions are not respected.
+ */
+#define BMK_TIMEDFNSTATE_SIZE 64
+typedef union {
+    char never_access_space[BMK_TIMEDFNSTATE_SIZE];
+    long long alignment_enforcer;  /* must be aligned on 8-bytes boundaries */
+} BMK_timedFnState_shell;
+BMK_timedFnState_t* BMK_initStatic_timedFnState(void* buffer, size_t size, unsigned total_ms, unsigned run_ms);
+
+
+#endif   /* BENCH_FN_H_23876 */
+
+#if defined (__cplusplus)
+}
+#endif