1 files changed, 144 insertions, 0 deletions
diff --git a/intl/icu/source/i18n/bocsu.cpp b/intl/icu/source/i18n/bocsu.cpp
new file mode 100644
index 0000000000..585415643b
--- /dev/null
+++ b/intl/icu/source/i18n/bocsu.cpp
@@ -0,0 +1,144 @@
+// © 2016 and later: Unicode, Inc. and others.
+// License & terms of use: http://www.unicode.org/copyright.html
+/*
+*******************************************************************************
+*   Copyright (C) 2001-2014, International Business Machines
+*   Corporation and others.  All Rights Reserved.
+*******************************************************************************
+*   file name:  bocsu.cpp
+*   encoding:   UTF-8
+*   tab size:   8 (not used)
+*   indentation:4
+*
+*   Author: Markus W. Scherer
+*
+*   Modification history:
+*   05/18/2001  weiv    Made into separate module
+*/
+
+
+#include "unicode/utypes.h"
+
+#if !UCONFIG_NO_COLLATION
+
+#include "unicode/bytestream.h"
+#include "unicode/utf16.h"
+#include "bocsu.h"
+
+/*
+ * encode one difference value -0x10ffff..+0x10ffff in 1..4 bytes,
+ * preserving lexical order
+ */
+static uint8_t *
+u_writeDiff(int32_t diff, uint8_t *p) {
+    if(diff>=SLOPE_REACH_NEG_1) {
+        if(diff<=SLOPE_REACH_POS_1) {
+            *p++=(uint8_t)(SLOPE_MIDDLE+diff);
+        } else if(diff<=SLOPE_REACH_POS_2) {
+            *p++=(uint8_t)(SLOPE_START_POS_2+(diff/SLOPE_TAIL_COUNT));
+            *p++=(uint8_t)(SLOPE_MIN+diff%SLOPE_TAIL_COUNT);
+        } else if(diff<=SLOPE_REACH_POS_3) {
+            p[2]=(uint8_t)(SLOPE_MIN+diff%SLOPE_TAIL_COUNT);
+            diff/=SLOPE_TAIL_COUNT;
+            p[1]=(uint8_t)(SLOPE_MIN+diff%SLOPE_TAIL_COUNT);
+            *p=(uint8_t)(SLOPE_START_POS_3+(diff/SLOPE_TAIL_COUNT));
+            p+=3;
+        } else {
+            p[3]=(uint8_t)(SLOPE_MIN+diff%SLOPE_TAIL_COUNT);
+            diff/=SLOPE_TAIL_COUNT;
+            p[2]=(uint8_t)(SLOPE_MIN+diff%SLOPE_TAIL_COUNT);
+            diff/=SLOPE_TAIL_COUNT;
+            p[1]=(uint8_t)(SLOPE_MIN+diff%SLOPE_TAIL_COUNT);
+            *p=SLOPE_MAX;
+            p+=4;
+        }
+    } else {
+        int32_t m;
+
+        if(diff>=SLOPE_REACH_NEG_2) {
+            NEGDIVMOD(diff, SLOPE_TAIL_COUNT, m);
+            *p++=(uint8_t)(SLOPE_START_NEG_2+diff);
+            *p++=(uint8_t)(SLOPE_MIN+m);
+        } else if(diff>=SLOPE_REACH_NEG_3) {
+            NEGDIVMOD(diff, SLOPE_TAIL_COUNT, m);
+            p[2]=(uint8_t)(SLOPE_MIN+m);
+            NEGDIVMOD(diff, SLOPE_TAIL_COUNT, m);
+            p[1]=(uint8_t)(SLOPE_MIN+m);
+            *p=(uint8_t)(SLOPE_START_NEG_3+diff);
+            p+=3;
+        } else {
+            NEGDIVMOD(diff, SLOPE_TAIL_COUNT, m);
+            p[3]=(uint8_t)(SLOPE_MIN+m);
+            NEGDIVMOD(diff, SLOPE_TAIL_COUNT, m);
+            p[2]=(uint8_t)(SLOPE_MIN+m);
+            NEGDIVMOD(diff, SLOPE_TAIL_COUNT, m);
+            p[1]=(uint8_t)(SLOPE_MIN+m);
+            *p=SLOPE_MIN;
+            p+=4;
+        }
+    }
+    return p;
+}
+
+/*
+ * Encode the code points of a string as
+ * a sequence of byte-encoded differences (slope detection),
+ * preserving lexical order.
+ *
+ * Optimize the difference-taking for runs of Unicode text within
+ * small scripts:
+ *
+ * Most small scripts are allocated within aligned 128-blocks of Unicode
+ * code points. Lexical order is preserved if "prev" is always moved
+ * into the middle of such a block.
+ *
+ * Additionally, "prev" is moved from anywhere in the Unihan
+ * area into the middle of that area.
+ * Note that the identical-level run in a sort key is generated from
+ * NFD text - there are never Hangul characters included.
+ */
+U_CFUNC UChar32
+u_writeIdenticalLevelRun(UChar32 prev, const char16_t *s, int32_t length, icu::ByteSink &sink) {
+    char scratch[64];
+    int32_t capacity;
+
+    int32_t i=0;
+    while(i<length) {
+        char *buffer=sink.GetAppendBuffer(1, length*2, scratch, (int32_t)sizeof(scratch), &capacity);
+        uint8_t *p;
+        // We must have capacity>=SLOPE_MAX_BYTES in case u_writeDiff() writes that much,
+        // but we do not want to force the sink.GetAppendBuffer() to allocate
+        // for a large min_capacity because we might actually only write one byte.
+        if(capacity<16) {
+            buffer=scratch;
+            capacity=(int32_t)sizeof(scratch);
+        }
+        p=reinterpret_cast<uint8_t *>(buffer);
+        uint8_t *lastSafe=p+capacity-SLOPE_MAX_BYTES;
+        while(i<length && p<=lastSafe) {
+            if(prev<0x4e00 || prev>=0xa000) {
+                prev=(prev&~0x7f)-SLOPE_REACH_NEG_1;
+            } else {
+                /*
+                 * Unihan U+4e00..U+9fa5:
+                 * double-bytes down from the upper end
+                 */
+                prev=0x9fff-SLOPE_REACH_POS_2;
+            }
+
+            UChar32 c;
+            U16_NEXT(s, i, length, c);
+            if(c==0xfffe) {
+                *p++=2;  // merge separator
+                prev=0;
+            } else {
+                p=u_writeDiff(c-prev, p);
+                prev=c;
+            }
+        }
+        sink.Append(buffer, (int32_t)(p-reinterpret_cast<uint8_t *>(buffer)));
+    }
+    return prev;
+}
+
+#endif /* #if !UCONFIG_NO_COLLATION */