MicroPython: Avoid heap usage.

* Use string_view in lieu of string * Rewrite _parse_escape_code to be compatible with string_view * Allocate a static buffer_t _SCREEN if DYNAMIC_BUFFER not set
pimoroni · Mar 15, 2023 · d5a56db · d5a56db
1 parent 639c1d2
commit d5a56db
Show file tree

Hide file tree

Showing 7 changed files with 54 additions and 23 deletions.
diff --git a/libraries/picosystem.cpp b/libraries/picosystem.cpp
@@ -24,12 +24,22 @@ namespace picosystem {
   #ifndef DYNAMIC_BUFFER
   #ifdef PIXEL_DOUBLE
     color_t _fb[120 * 120] __attribute__ ((aligned (4))) = { };
-    buffer_t *SCREEN = buffer(120, 120, _fb);
+    buffer_t _SCREEN = {
+      .w = 120,
+      .h = 120,
+      .data = (color_t *)&_fb
+    };
     int32_t _cx = 0, _cy = 0, _cw = 120, _ch = 120;
+    buffer_t *SCREEN = &_SCREEN;
   #else
     color_t _fb[240 * 240] __attribute__ ((aligned (4))) = { };
-    buffer_t *SCREEN = buffer(240, 240, _fb);
+    buffer_t _SCREEN = {
+      .w = 240,
+      .h = 240,
+      .data = (color_t *)&_fb
+    };
     int32_t _cx = 0, _cy = 0, _cw = 240, _ch = 240;
+    buffer_t *SCREEN = &_SCREEN;
   #endif
   #else
     buffer_t *SCREEN = nullptr;
@@ -41,7 +51,12 @@ namespace picosystem {
   #ifdef NO_SPRITESHEET
     buffer_t *_ss = nullptr;
   #else
-    buffer_t *SPRITESHEET = buffer(128, 128, (void *)_default_sprite_sheet);
+    buffer_t _SPRITESHEET = {
+      .w = 128,
+      .h = 128,
+      .data = (color_t *)_default_sprite_sheet
+    };
+    buffer_t *SPRITESHEET = &_SPRITESHEET;
     buffer_t *_ss = SPRITESHEET;
   #endif
 

diff --git a/libraries/picosystem.hpp b/libraries/picosystem.hpp
@@ -6,7 +6,9 @@
 #include <initializer_list>
 
 #include <string>
+#include <string_view>
 #include <vector>
+#include <charconv>
 
 #include "pico/stdlib.h"
 
@@ -139,11 +141,11 @@ namespace picosystem {
                 int32_t dw, int32_t dh, uint32_t flags);
   void        text(const char &c);
   void        text(
-                const std::string &t,
+                const std::string_view &t,
                 int32_t x, int32_t y,
                 int32_t wrap = -1);
   void        text(
-                const std::string &t,
+                const std::string_view &t,
                 int32_t wrap = -1);
 
   // blend functions
@@ -205,10 +207,10 @@ namespace picosystem {
                 int32_t  x, int32_t  y, int32_t  w, int32_t  h,
                 int32_t cx, int32_t cy, int32_t cw, int32_t ch);
   void        measure(
-                const std::string &t,
+                const std::string_view &t,
                 int32_t &w, int32_t &h,
                 int32_t wrap = -1);
-  std::vector<std::string> split(const std::string& t, char d = '\n');
+  std::vector<std::string_view> split(const std::string_view& t, char d = '\n');
   float       fsin(float v);
   float       fcos(float v);
   color_t     mix(color_t c1, color_t c2, uint8_t m);

diff --git a/libraries/text.cpp b/libraries/text.cpp
@@ -32,7 +32,7 @@ namespace picosystem {
     _tx += _char_width(c) + _tls;
   }
 
-  bool _matches(const std::string &t, const std::string &m, std::size_t &i) {
+  bool _matches(const std::string_view &t, const std::string_view &m, std::size_t &i) {
     std::size_t j = 0;
     while(j < m.size()) {
       if(t[i + j] != m[j]) {
@@ -46,7 +46,7 @@ namespace picosystem {
     return true;
   }
 
-  uint32_t _skip_escape_code(const std::string &t, std::size_t &i) {
+  uint32_t _skip_escape_code(const std::string_view &t, std::size_t &i) {
     uint32_t l = 0;
     i++;
     if(_matches(t, "pen", i)) {
@@ -60,7 +60,7 @@ namespace picosystem {
   }
 
   // search for end of the next word (including any e)
-  uint32_t _next_word_length(const std::string &t, std::size_t i) {
+  uint32_t _next_word_length(const std::string_view &t, std::size_t i) {
     // search through until we find a non word character to break on
     uint32_t l = 0;
     while(true) {
@@ -86,8 +86,8 @@ namespace picosystem {
     return 0;
   }
 
-  void _parse_escape_code(const std::string &t, std::size_t &i) {
-    i++;
+  void _parse_escape_code(const std::string_view &t, std::size_t &i) {
+    i++; // Skip the escape character
     if (_matches(t, "pen", i) ){
       uint8_t r = _hex_to_int(t[i++]);
       uint8_t g = _hex_to_int(t[i++]);
@@ -97,14 +97,17 @@ namespace picosystem {
     }
 
     if (_matches(t, "spr", i) ){
-      uint8_t si = std::stoi(t.substr(i, 3));
-      i += 2;
-      sprite(si, _tx, _ty);
-      _tx += 8;
+      uint8_t si;
+      auto result = std::from_chars(t.data() + i, t.data() + t.size(), si);
+      if(result.ec != std::errc::invalid_argument && result.ec != std::errc::result_out_of_range) {
+        i += result.ptr - t.data();
+        sprite(si, _tx, _ty);
+        _tx += 8;
+      }
     }
   }
 
-  void measure(const std::string &t, int32_t &w, int32_t &h, int32_t wrap) {
+  void measure(const std::string_view &t, int32_t &w, int32_t &h, int32_t wrap) {
     w = 0; h = 0;
 
     // save cursor position for wrapping new lines
@@ -155,7 +158,7 @@ namespace picosystem {
     h = ty + _tlh;
   }
 
-  void text(const std::string &t, int32_t wrap) {
+  void text(const std::string_view &t, int32_t wrap) {
     // save cursor position for wrapping new lines
     int32_t _stx = _tx;
     int32_t _wtx = _tx + wrap;
@@ -205,7 +208,7 @@ namespace picosystem {
     _tx = _stx;
   }
 
-  void text(const std::string &t, int32_t x, int32_t y, int32_t wrap) {
+  void text(const std::string_view &t, int32_t x, int32_t y, int32_t wrap) {
     _camera_offset(x, y);
     _tx = x; _ty = y;
     text(t, wrap);

diff --git a/micropython/modules/micropython.cmake b/micropython/modules/micropython.cmake
@@ -3,4 +3,8 @@ include_directories(${CMAKE_CURRENT_LIST_DIR}/../../)
 list(APPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_LIST_DIR}")
 list(APPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_LIST_DIR}/../../")
 
+# Enable support for string_view
+set(CMAKE_C_STANDARD 11)
+set(CMAKE_CXX_STANDARD 17)
+
 include(picosystem/micropython)
diff --git a/micropython/modules/picosystem/micropython.cmake b/micropython/modules/picosystem/micropython.cmake
@@ -32,6 +32,7 @@ target_include_directories(usermod_picosystem INTERFACE
 target_compile_definitions(usermod_picosystem INTERFACE
     MODULE_PICOSYSTEM_ENABLED=1
     PIXEL_DOUBLE=1
+    NO_OVERCLOCK=1
 )
 
 target_link_libraries(usermod_picosystem INTERFACE
@@ -52,6 +53,12 @@ set_source_files_properties(
     "-DPIXEL_DOUBLE=1"
 )
 
+set_source_files_properties(
+    ${CMAKE_CURRENT_LIST_DIR}/hardware.cpp
+    PROPERTIES COMPILE_FLAGS
+    "-DNO_OVERCLOCK=1"
+)
+
 # TODO fix sign compare issues in codebase
 set_source_files_properties(
     ${CMAKE_CURRENT_LIST_DIR}/../../../libraries/primitives.cpp

diff --git a/micropython/modules/picosystem/primitives.cpp b/micropython/modules/picosystem/primitives.cpp
@@ -134,7 +134,7 @@ mp_obj_t picosystem_poly(mp_uint_t n_args, const mp_obj_t *args) {
 
     if(num_tuples > 0) {
         size_t num_points = num_tuples * 2;
-        int32_t* points = new int32_t[num_points];
+        int32_t* points = m_new(int32_t, num_points);
         size_t i2 = 0;
         for(size_t i = 0; i < num_tuples; i++) {
             mp_obj_t obj = tuples[i];
@@ -152,7 +152,7 @@ mp_obj_t picosystem_poly(mp_uint_t n_args, const mp_obj_t *args) {
             }
         }
         poly(points, num_tuples);
-        delete[] points;
+        m_free(points);
     }
 
     return mp_const_none;

diff --git a/micropython/modules/picosystem/text.cpp b/micropython/modules/picosystem/text.cpp
@@ -13,7 +13,7 @@ mp_obj_t picosystem_text(mp_uint_t n_args, const mp_obj_t *args) {
     if(mp_obj_is_str_or_bytes(args[0])) {
         GET_STR_DATA_LEN(args[0], str, str_len);
 
-        std::string t((const char*)str);
+        std::string_view t((const char*)str, str_len);
 
         if(n_args == 4) {
             int x = mp_obj_get_int(args[1]);
@@ -46,7 +46,7 @@ mp_obj_t picosystem_measure(mp_uint_t n_args, const mp_obj_t *args) {
     if(mp_obj_is_str_or_bytes(str_obj)) {
         GET_STR_DATA_LEN(str_obj, str, str_len);
 
-        std::string t((const char*)str);
+        std::string_view t((const char*)str, str_len);
         int32_t w = 0;
         int32_t h = 0;
         int32_t wrap = n_args == 2 ? mp_obj_get_int(args[1]) : -1;