ESPTerm - ESP8266 terminal emulator. Branches: [master] patches, [work] next release
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espterm-firmware/user/utf8.c

209 lines
5.1 KiB

//
// Created by MightyPork on 2017/09/10.
//
#include <esp8266.h>
#include "utf8.h"
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typedef struct __attribute__((packed)) {
char bytes[4];
uint16_t count;
} UnicodeCacheSlot;
static UnicodeCacheSlot cache[UNICODE_CACHE_SIZE];
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#define REF_TO_ID(c) (u8)((c) >= 127 ? (c) - 95 : (c))
#define ID_TO_REF(c) (UnicodeCacheRef)((c) > 31 ? (c) + 95 : c)
/**
* Clear the entire cache
* @return
*/
void ICACHE_FLASH_ATTR
unicode_cache_clear(void)
{
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utfc_dbg("utf8 cache clear!");
for (int slot = 0; slot < UNICODE_CACHE_SIZE; slot++) {
cache[slot].count=0;
}
}
/**
* Add a code point to the cache. ASCII is passed through.
* If the code point is already stored, its use counter is incremented.
*
* @param bytes - utf8 bytes
* @return the obtained look-up reference
*/
UnicodeCacheRef ICACHE_FLASH_ATTR
unicode_cache_add(const u8 *bytes)
{
if (bytes[0] < 32) {
utfc_warn("utf8 cache bad char '%c'", bytes[0]);
return '?';
}
if (bytes[0] < 127) return bytes[0]; // ASCII, bypass
u8 slot;
for (slot = 0; slot < UNICODE_CACHE_SIZE; slot++) {
if (strneq(cache[slot].bytes, bytes, 4)) {
cache[slot].count++;
if (cache[slot].count == 1) {
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utfc_dbg("utf8 cache new '%.4s' @ %d", bytes, slot);
} else {
utfc_dbg("utf8 cache inc '%.4s' @ %d, %d uses", bytes, slot, cache[slot].count);
}
goto suc;
}
}
for (slot = 0; slot < UNICODE_CACHE_SIZE; slot++) {
if (cache[slot].count==0) {
// empty slot, store it
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strncpy(cache[slot].bytes, (const char *) bytes, 4); // this will zero out the remainder
cache[slot].count = 1;
utfc_dbg("utf8 cache new '%.4s' @ %d", bytes, slot);
goto suc;
}
}
error("utf8 cache full");
return '?'; // fallback to normal ASCII that will show to the user
suc:
return ID_TO_REF(slot);
}
/**
* Increment a reference
*
* @param ref - reference
* @return success
*/
bool ICACHE_FLASH_ATTR
unicode_cache_inc(UnicodeCacheRef ref)
{
if (!IS_UNICODE_CACHE_REF(ref)) return true; // ASCII
int slot = REF_TO_ID(ref);
if (cache[slot].count == 0) {
utfc_warn("utf8 cache inc-after-free ref @ %d", ref);
return false;
}
cache[slot].count++;
utfc_dbg("utf8 cache inc '%.4s' @ %d, %d uses", cache[slot].bytes, slot, cache[slot].count);
return true;
}
/**
* Look up a code point in the cache by reference. Do not change the use counter.
*
* @param ref - reference obtained earlier using unicode_cache_add()
* @param target - buffer of size 4 to hold the result.
* @return true if the look-up succeeded
*/
bool ICACHE_FLASH_ATTR
unicode_cache_retrieve(UnicodeCacheRef ref, u8 *target)
{
if (!IS_UNICODE_CACHE_REF(ref)) {
// ASCII, bypass
target[0] = ref;
target[1] = 0;
return true;
}
u8 slot = REF_TO_ID(ref);
if (cache[slot].count == 0) {
// "use after free"
target[0] = '?';
target[1] = 0;
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utfc_warn("utf8 cache use-after-free @ %d ('%.4s')", slot, cache[slot].bytes);
return false;
}
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//utfc_dbg("utf8 cache hit '%.4s' @ %d", cache[slot].bytes, slot, cache[slot].count);
strncpy((char*)target, cache[slot].bytes, 4);
return true;
}
/**
* Remove an occurence of a code point from the cache.
* If the code point is used more than once, the use counter is decremented.
*
* @param ref - reference to remove or reduce
* @return true if the code point was found in the cache
*/
bool ICACHE_FLASH_ATTR
unicode_cache_remove(UnicodeCacheRef ref)
{
if (!IS_UNICODE_CACHE_REF(ref)) return true; // ASCII, bypass
u8 slot = REF_TO_ID(ref);
if (cache[slot].count == 0) {
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utfc_warn("utf8 cache double-free @ %d ('%.4s')", slot, cache[slot].bytes);
return false;
}
cache[slot].count--;
if (cache[slot].count) {
utfc_dbg("utf8 cache sub '%.4s' @ %d, %d uses remain", cache[slot].bytes, slot, cache[slot].count);
} else {
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utfc_dbg("utf8 cache del '%.4s' @ %d", cache[slot].bytes, slot);
}
return true;
}
/**
* Encode a code point using UTF-8
*
* @param out - output buffer (min 4 characters), will be 0-terminated if shorten than 4
* @param utf - code point 0-0x10FFFF
* @return number of bytes on success, 0 on failure (also produces U+FFFD, which uses 3 bytes)
*/
int ICACHE_FLASH_ATTR
utf8_encode(char *out, uint32_t utf, bool surrogateFix)
{
// Skip the surrogate block (wtf, unicode???)
if (surrogateFix && utf >= 0xD800) {
utf += 0x800;
}
if (utf <= 0x7F) {
// Plain ASCII
out[0] = (char) utf;
out[1] = 0;
return 1;
}
else if (utf <= 0x07FF) {
// 2-byte unicode
out[0] = (char) (((utf >> 6) & 0x1F) | 0xC0);
out[1] = (char) (((utf >> 0) & 0x3F) | 0x80);
out[2] = 0;
return 2;
}
else if (utf <= 0xFFFF) {
// 3-byte unicode
out[0] = (char) (((utf >> 12) & 0x0F) | 0xE0);
out[1] = (char) (((utf >> 6) & 0x3F) | 0x80);
out[2] = (char) (((utf >> 0) & 0x3F) | 0x80);
out[3] = 0;
return 3;
}
else if (utf <= 0x10FFFF) {
// 4-byte unicode
out[0] = (char) (((utf >> 18) & 0x07) | 0xF0);
out[1] = (char) (((utf >> 12) & 0x3F) | 0x80);
out[2] = (char) (((utf >> 6) & 0x3F) | 0x80);
out[3] = (char) (((utf >> 0) & 0x3F) | 0x80);
// out[4] = 0;
return 4;
}
else {
// error - use replacement character
out[0] = (char) 0xEF;
out[1] = (char) 0xBF;
out[2] = (char) 0xBD;
out[3] = 0;
return 0;
}
}