WIP - utf8 iterator for C

core/embed/lib/display.c

@@ -99,9 +99,9 @@ void display_text_render_buffer(const char *text, int textlen, int font,
   int baseline = font_baseline(font);
 
   // render glyphs
-  for (int c_idx = 0; c_idx < textlen; c_idx++) {
-    const uint8_t *g = font_get_glyph(font, (uint8_t)text[c_idx]);
-    if (!g) continue;
+  font_glyph_iter_t iter = font_glyph_iter_init(font, (uint8_t *)text, textlen);
+  const uint8_t *g = NULL;
+  while (font_next_glyph(&iter, &g)) {
     const uint8_t w = g[0];      // width
     const uint8_t h = g[1];      // height
     const uint8_t adv = g[2];    // advance
@@ -307,9 +307,9 @@ static void display_text_render(int x, int y, const char *text, int textlen,
   set_color_table(colortable, fgcolor, bgcolor);
 
   // render glyphs
-  for (int c_idx = 0; c_idx < textlen; c_idx++) {
-    const uint8_t *g = font_get_glyph(font, (uint8_t)text[c_idx]);
-    if (!g) continue;
+  font_glyph_iter_t iter = font_glyph_iter_init(font, (uint8_t *)text, textlen);
+  const uint8_t *g = NULL;
+  while (font_next_glyph(&iter, &g)) {
     const uint8_t w = g[0];      // width
     const uint8_t h = g[1];      // height
     const uint8_t adv = g[2];    // advance
@@ -363,9 +363,9 @@ static void display_text_render(int x, int y, const char *text, int textlen,
   set_color_table(colortable, fgcolor, bgcolor);
 
   // render glyphs
-  for (int i = 0; i < textlen; i++) {
-    const uint8_t *g = font_get_glyph(font, (uint8_t)text[i]);
-    if (!g) continue;
+  font_glyph_iter_t iter = font_glyph_iter_init(font, (uint8_t *)text, textlen);
+  const uint8_t *g = NULL;
+  while (font_next_glyph(&iter, &g)) {
     const uint8_t w = g[0];      // width
     const uint8_t h = g[1];      // height
     const uint8_t adv = g[2];    // advance
@@ -433,9 +433,9 @@ int display_text_width(const char *text, int textlen, int font) {
   if (textlen < 0) {
     textlen = strlen(text);
   }
-  for (int i = 0; i < textlen; i++) {
-    const uint8_t *g = font_get_glyph(font, (uint8_t)text[i]);
-    if (!g) continue;
+  font_glyph_iter_t iter = font_glyph_iter_init(font, (uint8_t *)text, textlen);
+  const uint8_t *g = NULL;
+  while (font_next_glyph(&iter, &g)) {
     const uint8_t adv = g[2];  // advance
     width += adv;
     /*
@@ -452,35 +452,6 @@ int display_text_width(const char *text, int textlen, int font) {
   return width;
 }
 
-// Returns how many characters of the string can be used before exceeding
-// the requested width. Tries to avoid breaking words if possible.
-int display_text_split(const char *text, int textlen, int font,
-                       int requested_width) {
-  int width = 0;
-  int lastspace = 0;
-  // determine text length if not provided
-  if (textlen < 0) {
-    textlen = strlen(text);
-  }
-  for (int i = 0; i < textlen; i++) {
-    if (text[i] == ' ') {
-      lastspace = i;
-    }
-    const uint8_t *g = font_get_glyph(font, (uint8_t)text[i]);
-    if (!g) continue;
-    const uint8_t adv = g[2];  // advance
-    width += adv;
-    if (width > requested_width) {
-      if (lastspace > 0) {
-        return lastspace;
-      } else {
-        return i;
-      }
-    }
-  }
-  return textlen;
-}
-
 #ifdef TREZOR_PRODTEST
 
 #include "qr-code-generator/qrcodegen.h"

core/embed/lib/display.h

@@ -59,8 +59,6 @@ void display_text_center(int x, int y, const char *text, int textlen, int font,
 void display_text_right(int x, int y, const char *text, int textlen, int font,
                         uint16_t fgcolor, uint16_t bgcolor);
 int display_text_width(const char *text, int textlen, int font);
-int display_text_split(const char *text, int textlen, int font,
-                       int requested_width);
 void display_text_render_buffer(const char *text, int textlen, int font,
                                 buffer_text_t *buffer, int text_offset);
 

core/embed/lib/fonts/fonts.c

@@ -18,46 +18,14 @@
  */
 
 #include "fonts.h"
+#include <assert.h>
 #include <stdbool.h>
 #include <stddef.h>
 #ifdef TRANSLATIONS
 #include "librust_fonts.h"
 #endif
 
-// TODO: make it return uint32_t (needs logic to assemble at most 4 bytes
-// together)
-static uint16_t convert_char_utf8(const uint8_t c) {
-  // Considering only two-byte UTF-8 characters currently
-  static uint8_t first_utf8_byte = 0;
-
-  // non-printable ASCII character
-  if (c < ' ') {
-    first_utf8_byte = 0;
-    return 0x7F;
-  }
-
-  // regular ASCII character
-  if (c < 0x80) {
-    first_utf8_byte = 0;
-    return c;
-  }
-
-  // UTF-8 handling: https://en.wikipedia.org/wiki/UTF-8#Encoding
-
-  // bytes 11xxxxxx are first bytes of UTF-8 characters
-  if (c >= 0xC0) {
-    first_utf8_byte = c;
-    return 0;  // not print this
-  }
-
-  if (first_utf8_byte) {
-    // encountered a successive UTF-8 character ...
-    return ((uint16_t)first_utf8_byte << 8) | c;
-  } else {
-    // ... or they are just non-printable ASCII characters
-    return 0x7F;
-  }
-}
+#define UNICODE_BADCHAR 0xFFFD
 
 int font_height(int font) {
   switch (font) {
@@ -137,55 +105,76 @@ int font_baseline(int font) {
   return 0;
 }
 
-const uint8_t *font_get_glyph(int font, uint8_t c) {
-  uint16_t c_2bytes = convert_char_utf8(c);
-  if (!c_2bytes) return 0;
-  bool is_printable = c_2bytes != 0x7F;
+font_glyph_iter_t font_glyph_iter_init(const int font, const uint8_t *text,
+                                       const int len) {
+  return (font_glyph_iter_t){
+      .font = font,
+      .text = text,
+      .remaining = len,
+  };
+}
 
-#ifdef TRANSLATIONS
-  // found UTF8 character
-  // it is not hardcoded in firmware fonts, it must be extracted from the
-  // embedded blob
-  if (c_2bytes > 0xFF) {
-    PointerData glyph_data = get_utf8_glyph(c_2bytes, font);
-    // TODO: is it better to use (!glyph_data.ptr) or (glyph_data.ptr == NULL)?
-    // first one does not require import
-    if (glyph_data.ptr != NULL) {
-      return glyph_data.ptr;
-    } else {
-      is_printable = false;
-    }
+#define IS_UTF8_CONTINUE(c) (((c) & 0b11000000) == 0b10000000)
+
+static uint16_t next_utf8_codepoint(font_glyph_iter_t *iter) {
+  uint16_t out;
+  assert(iter->remaining > 0);
+  // 1-byte UTF-8 character
+  if (iter->text[0] < 0x7f) {
+    out = iter->text[0];
+    ++iter->text;
+    --iter->remaining;
+    return out;
   }
-#endif
-
-  // printable ASCII character
-  if (is_printable && c_2bytes >= ' ' && c_2bytes <= 126) {
-    switch (font) {
-#ifdef TREZOR_FONT_NORMAL_ENABLE
-      case FONT_NORMAL:
-        return FONT_NORMAL_DATA[c_2bytes - ' '];
-#endif
-#ifdef TREZOR_FONT_DEMIBOLD_ENABLE
-      case FONT_DEMIBOLD:
-        return FONT_DEMIBOLD_DATA[c_2bytes - ' '];
-#endif
-#ifdef TREZOR_FONT_BOLD_ENABLE
-      case FONT_BOLD:
-        return FONT_BOLD_DATA[c_2bytes - ' '];
-#endif
-#ifdef TREZOR_FONT_MONO_ENABLE
-      case FONT_MONO:
-        return FONT_MONO_DATA[c_2bytes - ' '];
-#endif
-#ifdef TREZOR_FONT_BIG_ENABLE
-      case FONT_BIG:
-        return FONT_BIG_DATA[c_2bytes - ' '];
-#endif
-    }
-    return 0;
+  // 2-byte UTF-8 character
+  if (iter->remaining >= 2 && ((iter->text[0] & 0b11100000) == 0b11000000) &&
+      IS_UTF8_CONTINUE(iter->text[1])) {
+    out = (((uint16_t)iter->text[0] & 0b00011111) << 6) |
+          (iter->text[1] & 0b00111111);
+    iter->text += 2;
+    iter->remaining -= 2;
+    return out;
+  }
+  // 3-byte UTF-8 character
+  if (iter->remaining >= 3 && ((iter->text[0] & 0b11110000) == 0b11100000) &&
+      IS_UTF8_CONTINUE(iter->text[1]) && IS_UTF8_CONTINUE(iter->text[2])) {
+    out = (((uint16_t)iter->text[0] & 0b00001111) << 12) |
+          (((uint16_t)iter->text[1] & 0b00111111) << 6) |
+          (iter->text[2] & 0b00111111);
+    iter->text += 3;
+    iter->remaining -= 3;
+    return out;
+  }
+  // 4-byte UTF-8 character
+  if (iter->remaining >= 4 && ((iter->text[0] & 0b11111000) == 0b11110000) &&
+      IS_UTF8_CONTINUE(iter->text[1]) && IS_UTF8_CONTINUE(iter->text[2]) &&
+      IS_UTF8_CONTINUE(iter->text[3])) {
+    // we use 16-bit codepoints, so we can't represent 4-byte UTF-8 characters
+    iter->text += 4;
+    iter->remaining -= 4;
+    return UNICODE_BADCHAR;
   }
 
-// non-printable character
+  ++iter->text;
+  --iter->remaining;
+  return UNICODE_BADCHAR;
+}
+
+bool font_next_glyph(font_glyph_iter_t *iter, const uint8_t **out) {
+  if (iter->remaining <= 0) {
+    return false;
+  }
+  uint16_t c = next_utf8_codepoint(iter);
+  *out = font_get_glyph(iter->font, c);
+  if (*out == NULL) {
+    // should not happen but ¯\_(ツ)_/¯
+    return font_next_glyph(iter, out);
+  } else {
+    return true;
+  }
+}
+
+const uint8_t *font_nonprintable_glyph(int font) {
 #define PASTER(s) s##_glyph_nonprintable
 #define NONPRINTABLE_GLYPH(s) PASTER(s)
 
@@ -210,6 +199,50 @@ const uint8_t *font_get_glyph(int font, uint8_t c) {
     case FONT_BIG:
       return NONPRINTABLE_GLYPH(FONT_BIG_DATA);
 #endif
+    default:
+      return NULL;
   }
-  return 0;
+}
+
+const uint8_t *font_get_glyph(int font, uint16_t c) {
+#ifdef TRANSLATIONS
+  // found UTF8 character
+  // it is not hardcoded in firmware fonts, it must be extracted from the
+  // embedded blob
+  if (c >= 0x7F) {
+    const uint8_t *g = get_utf8_glyph(c, font);
+    if (g != NULL) {
+      return g;
+    }
+  }
+#endif
+
+  // printable ASCII character
+  if (c >= ' ' && c < 0x7F) {
+    switch (font) {
+#ifdef TREZOR_FONT_NORMAL_ENABLE
+      case FONT_NORMAL:
+        return FONT_NORMAL_DATA[c - ' '];
+#endif
+#ifdef TREZOR_FONT_DEMIBOLD_ENABLE
+      case FONT_DEMIBOLD:
+        return FONT_DEMIBOLD_DATA[c - ' '];
+#endif
+#ifdef TREZOR_FONT_BOLD_ENABLE
+      case FONT_BOLD:
+        return FONT_BOLD_DATA[c - ' '];
+#endif
+#ifdef TREZOR_FONT_MONO_ENABLE
+      case FONT_MONO:
+        return FONT_MONO_DATA[c - ' '];
+#endif
+#ifdef TREZOR_FONT_BIG_ENABLE
+      case FONT_BIG:
+        return FONT_BIG_DATA[c - ' '];
+#endif
+    }
+    return 0;
+  }
+
+  return font_nonprintable_glyph(font);
 }

core/embed/lib/fonts/fonts.h

@@ -20,6 +20,8 @@
 #ifndef _FONTS_H
 #define _FONTS_H
 
+#include <stdbool.h>
+
 #include "fonts/font_bitmap.h"
 #include TREZOR_BOARD
 
@@ -117,6 +119,17 @@
 int font_height(int font);
 int font_max_height(int font);
 int font_baseline(int font);
-const uint8_t *font_get_glyph(int font, uint8_t c);
+const uint8_t *font_get_glyph(int font, uint16_t c);
+const uint8_t *font_nonprintable_glyph(int font);
+
+typedef struct {
+  const int font;
+  const uint8_t *text;
+  int remaining;
+} font_glyph_iter_t;
+
+font_glyph_iter_t font_glyph_iter_init(const int font, const uint8_t *text,
+                                       const int len);
+bool font_next_glyph(font_glyph_iter_t *iter, const uint8_t **out);
 
 #endif  //_FONTS_H