skia2/include/core/SkUtils.h

/*
 * Copyright 2006 The Android Open Source Project
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#ifndef SkUtils_DEFINED
#define SkUtils_DEFINED

#include "SkTypes.h"

namespace SkOpts {
    extern void (*memset16)(uint16_t[], uint16_t, int);
    extern void (*memset32)(uint32_t[], uint32_t, int);
}

///////////////////////////////////////////////////////////////////////////////

// Inlining heuristics were determined by using perf.skia.org and bench/MemsetBench.cpp.
// When using MSVC, inline is better >= 1K and worse <= 100.  The Nexus Player was the opposite.
// Otherwise, when NEON or SSE is available to GCC or Clang, they can handle it best.
// See https://code.google.com/p/chromium/issues/detail?id=516426#c15 for more details.
// See also skia:4316; it might be a good idea to use rep stosw/stosd here.
#define INLINE_IF(cond) if (cond) { while (count --> 0) { *buffer++ = value; } return; }

/** Similar to memset(), but it assigns a 16bit value into the buffer.
    @param buffer   The memory to have value copied into it
    @param value    The 16bit value to be copied into buffer
    @param count    The number of times value should be copied into the buffer.
*/
static inline void sk_memset16(uint16_t buffer[], uint16_t value, int count) {
#if defined(_MSC_VER)
    INLINE_IF(count > 300)
#elif defined(SK_BUILD_FOR_ANDROID) && defined(SK_CPU_X86)
    INLINE_IF(count < 300)
#elif defined(SK_ARM_HAS_NEON) || SK_CPU_SSE_LEVEL >= SK_CPU_SSE_LEVEL_SSE2
    INLINE_IF(true)
#else
    INLINE_IF(count <= 10)
#endif
    SkOpts::memset16(buffer, value, count);
}

/** Similar to memset(), but it assigns a 32bit value into the buffer.
    @param buffer   The memory to have value copied into it
    @param value    The 32bit value to be copied into buffer
    @param count    The number of times value should be copied into the buffer.
*/
static inline void sk_memset32(uint32_t buffer[], uint32_t value, int count) {
#if defined(_MSC_VER)
    INLINE_IF(count > 300)
#elif defined(SK_BUILD_FOR_ANDROID) && defined(SK_CPU_X86)
    INLINE_IF(count < 300)
#elif defined(SK_ARM_HAS_NEON) || SK_CPU_SSE_LEVEL >= SK_CPU_SSE_LEVEL_SSE2
    INLINE_IF(true)
#else
    INLINE_IF(count <= 10)
#endif
    SkOpts::memset32(buffer, value, count);
}

#undef INLINE_IF

///////////////////////////////////////////////////////////////////////////////

#define kMaxBytesInUTF8Sequence     4

#ifdef SK_DEBUG
    int SkUTF8_LeadByteToCount(unsigned c);
#else
    #define SkUTF8_LeadByteToCount(c)   ((((0xE5 << 24) >> ((unsigned)c >> 4 << 1)) & 3) + 1)
#endif

inline int SkUTF8_CountUTF8Bytes(const char utf8[]) {
    SkASSERT(utf8);
    return SkUTF8_LeadByteToCount(*(const uint8_t*)utf8);
}

int         SkUTF8_CountUnichars(const char utf8[]);
int         SkUTF8_CountUnichars(const char utf8[], size_t byteLength);
SkUnichar   SkUTF8_ToUnichar(const char utf8[]);
SkUnichar   SkUTF8_NextUnichar(const char**);
SkUnichar   SkUTF8_PrevUnichar(const char**);

/** Return the number of bytes need to convert a unichar
    into a utf8 sequence. Will be 1..kMaxBytesInUTF8Sequence,
    or 0 if uni is illegal.
*/
size_t      SkUTF8_FromUnichar(SkUnichar uni, char utf8[] = NULL);

///////////////////////////////////////////////////////////////////////////////

#define SkUTF16_IsHighSurrogate(c)  (((c) & 0xFC00) == 0xD800)
#define SkUTF16_IsLowSurrogate(c)   (((c) & 0xFC00) == 0xDC00)

int SkUTF16_CountUnichars(const uint16_t utf16[]);
int SkUTF16_CountUnichars(const uint16_t utf16[], int numberOf16BitValues);
// returns the current unichar and then moves past it (*p++)
SkUnichar SkUTF16_NextUnichar(const uint16_t**);
// this guy backs up to the previus unichar value, and returns it (*--p)
SkUnichar SkUTF16_PrevUnichar(const uint16_t**);
size_t SkUTF16_FromUnichar(SkUnichar uni, uint16_t utf16[] = NULL);

size_t SkUTF16_ToUTF8(const uint16_t utf16[], int numberOf16BitValues,
                      char utf8[] = NULL);

inline bool SkUnichar_IsVariationSelector(SkUnichar uni) {
/*  The 'true' ranges are:
 *      0x180B  <= uni <=  0x180D
 *      0xFE00  <= uni <=  0xFE0F
 *      0xE0100 <= uni <= 0xE01EF
 */
    if (uni < 0x180B || uni > 0xE01EF) {
        return false;
    }
    if ((uni > 0x180D && uni < 0xFE00) || (uni > 0xFE0F && uni < 0xE0100)) {
        return false;
    }
    return true;
}

///////////////////////////////////////////////////////////////////////////////

class SkAutoTrace {
public:
    /** NOTE: label contents are not copied, just the ptr is
        retained, so DON'T DELETE IT.
    */
    SkAutoTrace(const char label[]) : fLabel(label) {
        SkDebugf("--- trace: %s Enter\n", fLabel);
    }
    ~SkAutoTrace() {
        SkDebugf("--- trace: %s Leave\n", fLabel);
    }
private:
    const char* fLabel;
};
#define SkAutoTrace(...) SK_REQUIRE_LOCAL_VAR(SkAutoTrace)

#endif