optionally move float emulation code into iram (#8958)

* optionally move float emulation code into iram
allows doing float operation in iram
suitable for libraries like AccelStepper when called from ISR
* proposed changes for pio from @mcspr

tools/boards.txt.py

@@ -1682,6 +1682,17 @@ def sdk ():
 
 ################################################################
 
+def float_in_iram ():
+    return { 'iramfloat': collections.OrderedDict([
+                        ('.menu.iramfloat.no', 'in IROM'),
+                        ('.menu.iramfloat.no.build.iramfloat', '-DFP_IN_IROM'),
+                        ('.menu.iramfloat.yes', 'allowed in ISR'),
+                        ('.menu.iramfloat.yes.build.iramfloat', '-DFP_IN_IRAM'),
+                    ])
+           }
+
+################################################################
+
 def all_boards ():
 
     if boardsgen or boardslocalgen:
@@ -1709,6 +1720,7 @@ def all_boards ():
     macros.update(led('led',    led_default, range(0,led_max+1)))
     macros.update(led('led216', 2,           { 16 }))
     macros.update(sdk())
+    macros.update(float_in_iram())
 
     if boardfilteropt or excludeboards:
         print('#')
@@ -1754,6 +1766,7 @@ def all_boards ():
     print('menu.stacksmash=Stack Protection')
     print('menu.wipe=Erase Flash')
     print('menu.sdk=NONOS SDK Version')
+    print('menu.iramfloat=Floating Point operations')
     print('menu.ssl=SSL Support')
     print('menu.mmu=MMU')
     print('menu.non32xfer=Non-32-Bit Access')
@@ -1791,6 +1804,7 @@ def all_boards ():
             macrolist += speeds[default_speed]
 
         macrolist += [ 'autoflash' ]
+        macrolist += [ 'iramfloat' ]
 
         for block in macrolist:
             for optname in macros[block]:

tools/platformio-build.py

@@ -275,17 +275,23 @@ else:
 #
 
 current_vtables = None
-fp_in_irom = ""
+current_fp = None
 for d in flatten_cppdefines:
     if str(d).startswith("VTABLES_IN_"):
         current_vtables = d
-    if str(d) == "FP_IN_IROM":
-        fp_in_irom = "-DFP_IN_IROM"
+    if str(d).startswith("FP_IN_"):
+        current_fp = d
+
 if not current_vtables:
     current_vtables = "VTABLES_IN_FLASH"
     env.Append(CPPDEFINES=[current_vtables])
 assert current_vtables
 
+if not current_fp:
+    current_fp = "FP_IN_IROM"
+    env.Append(CPPDEFINES=[current_fp])
+assert current_fp
+
 #
 # MMU
 #
@@ -363,9 +369,10 @@ app_ld = env.Command(
     join("$BUILD_DIR", "ld", "local.eagle.app.v6.common.ld"),
     join(FRAMEWORK_DIR, "tools", "sdk", "ld", "eagle.app.v6.common.ld.h"),
     env.VerboseAction(
-        "$CC -CC -E -P -D%s %s %s $SOURCE -o $TARGET"
+        "$CC -CC -E -P -D%s -D%s %s $SOURCE -o $TARGET"
         % (
             current_vtables,
+            current_fp,
             # String representation of MMU flags
             " ".join(
                 [
@@ -373,7 +380,6 @@ app_ld = env.Command(
                     for f in mmu_flags
                 ]
             ),
-            fp_in_irom,
         ),
         "Generating LD script $TARGET",
     ),

tools/sdk/ld/eagle.app.v6.common.ld.h

@@ -142,6 +142,16 @@ SECTIONS
 
     /* all functional callers are placed in IRAM (including SPI/IRQ callbacks/etc) here */
     *(.text._ZNKSt8functionIF*EE*)  /* std::function<any(...)>::operator()() const */
+
+#ifdef FP_IN_IRAM
+    *libgcc.a:*f2.o(.literal .text)
+    *libgcc.a:*f3.o(.literal .text)
+    *libgcc.a:*fsi.o(.literal .text)
+    *libgcc.a:*fdi.o(.literal .text)
+    *libgcc.a:*ifs.o(.literal .text)
+    *libgcc.a:*idf.o(.literal .text)
+#endif
+
   } >iram1_0_seg :iram1_0_phdr
 
   .irom0.text : ALIGN(4)