IR lib FlashString handling

[kmihaylov]

This is not Sming issue, but something that I can't figure out. I'm trying to port the latest IR lib to Sming and I stuck with IR's FlashStrings not built with Sming.

First let me show the compiler error:

Building /home/opt/Sming/Sming/out/Esp8266/debug/lib/clib-IR.a
C+ /home/opt/Sming/Sming/Libraries/IR/src/ir_Carrier.cpp
/home/opt/Sming/Sming/Libraries/IR/src/ir_Carrier.cpp: In member function 'String IRCarrierAc64::toString() const':
/home/opt/Sming/Sming/Libraries/IR/src/ir_Carrier.cpp:493:38: error: could not convert 'kPowerStr' from 'const __FlashStringHelper* const' to 'String'
  493 |   result += addBoolToString(_.Power, kPowerStr, false);
      |                                      ^~~~~~~~~
      |                                      |
      |                                      const __FlashStringHelper* const

The variable kPowerStr is defined in IRtext.cpp. I'm posting the macros:

#define IRTEXT_CONST_BLOB_NAME(NAME)\
    NAME ## Blob

#define IRTEXT_CONST_BLOB_DECL(NAME)\
    const char IRTEXT_CONST_BLOB_NAME(NAME) [] PROGMEM

#define IRTEXT_CONST_BLOB_PTR(NAME)\
    IRTEXT_CONST_PTR(NAME) {\
        IRTEXT_CONST_PTR_CAST(IRTEXT_CONST_BLOB_NAME(NAME)) }

#define IRTEXT_CONST_STRING(NAME, VALUE)\
    static IRTEXT_CONST_BLOB_DECL(NAME) { VALUE };\
    IRTEXT_CONST_PTR(NAME) PROGMEM {\
        IRTEXT_CONST_PTR_CAST(&(IRTEXT_CONST_BLOB_NAME(NAME))[0]) }

and

IRTEXT_CONST_STRING(kPowerStr, D_STR_POWER);  ///< "Power"

Then Eclipse evaluated the macro to:

static const char kPowerStrBlob [] __attribute__((aligned(4))) { "Power" };
const char* const kPowerStr __attribute__((aligned(4))) {&(kPowerStrBlob)[0] }

where PROGMEM is(?) __attribute__((aligned(4))) (Looking in the header files I thing it should be something longer...?

I don't know how const char* const went to const __FlashStringHelper* const. I'm reading https://sming.readthedocs.io/en/latest/framework/core/pgmspace.html w/o luck.

[mikee47]

The constructor is delcared explicit String(flash_string_t pstr) so you'll need to modify code like this:

result += addBoolToString(_.Power, String(kPowerStr), false);

[mikee47]

On further inspection, the FlashString library can handle all this more easily. See https://github.com/mikee47/IRremoteESP8266/tree/sming. Builds but not tested.

[kmihaylov]

@mikee47 thanks.

Do I understand properly that String(kPowerStr) will copy the flash string to RAM?

The library heavily uses *Str like the above mentioned kPowerStr. I have no problem to modify all the files to String(...), but is this the best way? Is this some Arduino thing that the flash strings can be directly used?

---

Just saw your commit. I'll test in the afternoon.

[kmihaylov]

IR receive works just fine. I can solder second board to check IR send.

[mikee47]

Assuming resolved