SkUtils.cpp revision 48552314f6d101f3fd094d5f2fd6f70fe9aad841 
1
2/*
3 * Copyright 2006 The Android Open Source Project
4 *
5 * Use of this source code is governed by a BSD-style license that can be
6 * found in the LICENSE file.
7 */
8
9
10#include "SkUtils.h"
11
12#if 0
13#define assign_16_longs(dst, value)             \
14    do {                                        \
15        (dst)[0] = value;   (dst)[1] = value;   \
16        (dst)[2] = value;   (dst)[3] = value;   \
17        (dst)[4] = value;   (dst)[5] = value;   \
18        (dst)[6] = value;   (dst)[7] = value;   \
19        (dst)[8] = value;   (dst)[9] = value;   \
20        (dst)[10] = value;  (dst)[11] = value;  \
21        (dst)[12] = value;  (dst)[13] = value;  \
22        (dst)[14] = value;  (dst)[15] = value;  \
23    } while (0)
24#else
25#define assign_16_longs(dst, value)             \
26    do {                                        \
27        *(dst)++ = value;   *(dst)++ = value;   \
28        *(dst)++ = value;   *(dst)++ = value;   \
29        *(dst)++ = value;   *(dst)++ = value;   \
30        *(dst)++ = value;   *(dst)++ = value;   \
31        *(dst)++ = value;   *(dst)++ = value;   \
32        *(dst)++ = value;   *(dst)++ = value;   \
33        *(dst)++ = value;   *(dst)++ = value;   \
34        *(dst)++ = value;   *(dst)++ = value;   \
35    } while (0)
36#endif
37
38///////////////////////////////////////////////////////////////////////////////
39
40void sk_memset16_portable(uint16_t dst[], uint16_t value, int count) {
41    SkASSERT(dst != NULL && count >= 0);
42
43    if (count <= 0) {
44        return;
45    }
46
47    // not sure if this helps to short-circuit on small values of count
48    if (count < 8) {
49        do {
50            *dst++ = (uint16_t)value;
51        } while (--count != 0);
52        return;
53    }
54
55    // ensure we're on a long boundary
56    if ((size_t)dst & 2) {
57        *dst++ = (uint16_t)value;
58        count -= 1;
59    }
60
61    uint32_t value32 = ((uint32_t)value << 16) | value;
62
63    // handle the bulk with our unrolled macro
64    {
65        int sixteenlongs = count >> 5;
66        if (sixteenlongs) {
67            uint32_t* dst32 = (uint32_t*)dst;
68            do {
69                assign_16_longs(dst32, value32);
70            } while (--sixteenlongs != 0);
71            dst = (uint16_t*)dst32;
72            count &= 31;
73        }
74    }
75
76    // handle (most) of the rest
77    {
78        int longs = count >> 1;
79        if (longs) {
80            do {
81                *(uint32_t*)dst = value32;
82                dst += 2;
83            } while (--longs != 0);
84        }
85    }
86
87    // cleanup a possible trailing short
88    if (count & 1) {
89        *dst = (uint16_t)value;
90    }
91}
92
93void sk_memset32_portable(uint32_t dst[], uint32_t value, int count) {
94    SkASSERT(dst != NULL && count >= 0);
95
96    int sixteenlongs = count >> 4;
97    if (sixteenlongs) {
98        do {
99            assign_16_longs(dst, value);
100        } while (--sixteenlongs != 0);
101        count &= 15;
102    }
103
104    if (count) {
105        do {
106            *dst++ = value;
107        } while (--count != 0);
108    }
109}
110
111static void sk_memset16_stub(uint16_t dst[], uint16_t value, int count) {
112    SkMemset16Proc proc = SkMemset16GetPlatformProc();
113    sk_memset16 = proc ? proc : sk_memset16_portable;
114    sk_memset16(dst, value, count);
115}
116
117SkMemset16Proc sk_memset16 = sk_memset16_stub;
118
119static void sk_memset32_stub(uint32_t dst[], uint32_t value, int count) {
120    SkMemset32Proc proc = SkMemset32GetPlatformProc();
121    sk_memset32 = proc ? proc : sk_memset32_portable;
122    sk_memset32(dst, value, count);
123}
124
125SkMemset32Proc sk_memset32 = sk_memset32_stub;
126
127///////////////////////////////////////////////////////////////////////////////
128
129/*  0xxxxxxx    1 total
130    10xxxxxx    // never a leading byte
131    110xxxxx    2 total
132    1110xxxx    3 total
133    11110xxx    4 total
134
135    11 10 01 01 xx xx xx xx 0...
136    0xE5XX0000
137    0xE5 << 24
138*/
139
140#ifdef SK_DEBUG
141    static void assert_utf8_leadingbyte(unsigned c) {
142        SkASSERT(c <= 0xF7);    // otherwise leading byte is too big (more than 4 bytes)
143        SkASSERT((c & 0xC0) != 0x80);   // can't begin with a middle char
144    }
145
146    int SkUTF8_LeadByteToCount(unsigned c) {
147        assert_utf8_leadingbyte(c);
148        return (((0xE5 << 24) >> (c >> 4 << 1)) & 3) + 1;
149    }
150#else
151    #define assert_utf8_leadingbyte(c)
152#endif
153
154int SkUTF8_CountUnichars(const char utf8[]) {
155    SkASSERT(utf8);
156
157    int count = 0;
158
159    for (;;) {
160        int c = *(const uint8_t*)utf8;
161        if (c == 0) {
162            break;
163        }
164        utf8 += SkUTF8_LeadByteToCount(c);
165        count += 1;
166    }
167    return count;
168}
169
170int SkUTF8_CountUnichars(const char utf8[], size_t byteLength) {
171    SkASSERT(NULL != utf8 || 0 == byteLength);
172
173    int         count = 0;
174    const char* stop = utf8 + byteLength;
175
176    while (utf8 < stop) {
177        utf8 += SkUTF8_LeadByteToCount(*(const uint8_t*)utf8);
178        count += 1;
179    }
180    return count;
181}
182
183SkUnichar SkUTF8_ToUnichar(const char utf8[]) {
184    SkASSERT(NULL != utf8);
185
186    const uint8_t*  p = (const uint8_t*)utf8;
187    int             c = *p;
188    int             hic = c << 24;
189
190    assert_utf8_leadingbyte(c);
191
192    if (hic < 0) {
193        uint32_t mask = (uint32_t)~0x3F;
194        hic <<= 1;
195        do {
196            c = (c << 6) | (*++p & 0x3F);
197            mask <<= 5;
198        } while ((hic <<= 1) < 0);
199        c &= ~mask;
200    }
201    return c;
202}
203
204SkUnichar SkUTF8_NextUnichar(const char** ptr) {
205    SkASSERT(NULL != ptr && NULL != *ptr);
206
207    const uint8_t*  p = (const uint8_t*)*ptr;
208    int             c = *p;
209    int             hic = c << 24;
210
211    assert_utf8_leadingbyte(c);
212
213    if (hic < 0) {
214        uint32_t mask = (uint32_t)~0x3F;
215        hic <<= 1;
216        do {
217            c = (c << 6) | (*++p & 0x3F);
218            mask <<= 5;
219        } while ((hic <<= 1) < 0);
220        c &= ~mask;
221    }
222    *ptr = (char*)p + 1;
223    return c;
224}
225
226SkUnichar SkUTF8_PrevUnichar(const char** ptr) {
227    SkASSERT(NULL != ptr && NULL != *ptr);
228
229    const char* p = *ptr;
230
231    if (*--p & 0x80) {
232        while (*--p & 0x40) {
233            ;
234        }
235    }
236
237    *ptr = (char*)p;
238    return SkUTF8_NextUnichar(&p);
239}
240
241size_t SkUTF8_FromUnichar(SkUnichar uni, char utf8[]) {
242    if ((uint32_t)uni > 0x10FFFF) {
243        SkDEBUGFAIL("bad unichar");
244        return 0;
245    }
246
247    if (uni <= 127) {
248        if (utf8) {
249            *utf8 = (char)uni;
250        }
251        return 1;
252    }
253
254    char    tmp[4];
255    char*   p = tmp;
256    size_t  count = 1;
257
258    SkDEBUGCODE(SkUnichar orig = uni;)
259
260    while (uni > 0x7F >> count) {
261        *p++ = (char)(0x80 | (uni & 0x3F));
262        uni >>= 6;
263        count += 1;
264    }
265
266    if (utf8) {
267        p = tmp;
268        utf8 += count;
269        while (p < tmp + count - 1) {
270            *--utf8 = *p++;
271        }
272        *--utf8 = (char)(~(0xFF >> count) | uni);
273    }
274
275    SkASSERT(utf8 == NULL || orig == SkUTF8_ToUnichar(utf8));
276    return count;
277}
278
279///////////////////////////////////////////////////////////////////////////////
280
281int SkUTF16_CountUnichars(const uint16_t src[]) {
282    SkASSERT(src);
283
284    int count = 0;
285    unsigned c;
286    while ((c = *src++) != 0) {
287        SkASSERT(!SkUTF16_IsLowSurrogate(c));
288        if (SkUTF16_IsHighSurrogate(c)) {
289            c = *src++;
290            SkASSERT(SkUTF16_IsLowSurrogate(c));
291        }
292        count += 1;
293    }
294    return count;
295}
296
297int SkUTF16_CountUnichars(const uint16_t src[], int numberOf16BitValues) {
298    SkASSERT(src);
299
300    const uint16_t* stop = src + numberOf16BitValues;
301    int count = 0;
302    while (src < stop) {
303        unsigned c = *src++;
304        SkASSERT(!SkUTF16_IsLowSurrogate(c));
305        if (SkUTF16_IsHighSurrogate(c)) {
306            SkASSERT(src < stop);
307            c = *src++;
308            SkASSERT(SkUTF16_IsLowSurrogate(c));
309        }
310        count += 1;
311    }
312    return count;
313}
314
315SkUnichar SkUTF16_NextUnichar(const uint16_t** srcPtr) {
316    SkASSERT(srcPtr && *srcPtr);
317
318    const uint16_t* src = *srcPtr;
319    SkUnichar       c = *src++;
320
321    SkASSERT(!SkUTF16_IsLowSurrogate(c));
322    if (SkUTF16_IsHighSurrogate(c)) {
323        unsigned c2 = *src++;
324        SkASSERT(SkUTF16_IsLowSurrogate(c2));
325
326        // c = ((c & 0x3FF) << 10) + (c2 & 0x3FF) + 0x10000
327        // c = (((c & 0x3FF) + 64) << 10) + (c2 & 0x3FF)
328        c = (c << 10) + c2 + (0x10000 - (0xD800 << 10) - 0xDC00);
329    }
330    *srcPtr = src;
331    return c;
332}
333
334SkUnichar SkUTF16_PrevUnichar(const uint16_t** srcPtr) {
335    SkASSERT(srcPtr && *srcPtr);
336
337    const uint16_t* src = *srcPtr;
338    SkUnichar       c = *--src;
339
340    SkASSERT(!SkUTF16_IsHighSurrogate(c));
341    if (SkUTF16_IsLowSurrogate(c)) {
342        unsigned c2 = *--src;
343        SkASSERT(SkUTF16_IsHighSurrogate(c2));
344        c = (c2 << 10) + c + (0x10000 - (0xD800 << 10) - 0xDC00);
345    }
346    *srcPtr = src;
347    return c;
348}
349
350size_t SkUTF16_FromUnichar(SkUnichar uni, uint16_t dst[]) {
351    SkASSERT((unsigned)uni <= 0x10FFFF);
352
353    int extra = (uni > 0xFFFF);
354
355    if (dst) {
356        if (extra) {
357            // dst[0] = SkToU16(0xD800 | ((uni - 0x10000) >> 10));
358            // dst[0] = SkToU16(0xD800 | ((uni >> 10) - 64));
359            dst[0] = SkToU16((0xD800 - 64) + (uni >> 10));
360            dst[1] = SkToU16(0xDC00 | (uni & 0x3FF));
361
362            SkASSERT(SkUTF16_IsHighSurrogate(dst[0]));
363            SkASSERT(SkUTF16_IsLowSurrogate(dst[1]));
364        } else {
365            dst[0] = SkToU16(uni);
366            SkASSERT(!SkUTF16_IsHighSurrogate(dst[0]));
367            SkASSERT(!SkUTF16_IsLowSurrogate(dst[0]));
368        }
369    }
370    return 1 + extra;
371}
372
373size_t SkUTF16_ToUTF8(const uint16_t utf16[], int numberOf16BitValues,
374                      char utf8[]) {
375    SkASSERT(numberOf16BitValues >= 0);
376    if (numberOf16BitValues <= 0) {
377        return 0;
378    }
379
380    SkASSERT(utf16 != NULL);
381
382    const uint16_t* stop = utf16 + numberOf16BitValues;
383    size_t          size = 0;
384
385    if (utf8 == NULL) {    // just count
386        while (utf16 < stop) {
387            size += SkUTF8_FromUnichar(SkUTF16_NextUnichar(&utf16), NULL);
388        }
389    } else {
390        char* start = utf8;
391        while (utf16 < stop) {
392            utf8 += SkUTF8_FromUnichar(SkUTF16_NextUnichar(&utf16), utf8);
393        }
394        size = utf8 - start;
395    }
396    return size;
397}
398