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

Author: d-a-v

boards.txt

@@ -263,6 +263,12 @@ See our issue tracker in regards to default version selection.
 
 Notice that 3.x.x is provided **as-is** and remains **experimental**.
 
+Floating Point operations
+~~~~~~~~~~~~~~~~~~~~~~~~~
+
+- ``in IROM``: This provides more free space in IRAM but disallows using floating operations inside ISRs.
+- ``allowed in ISR``: Floats can be used in ISRs, cost is ~1KB IRAM when floats are used.
+
 SSL Support
 ~~~~~~~~~~~
 

doc/ideoptions.rst

@@ -383,4 +383,4 @@
          ]
       }
    ]
-}
+}

package/package_esp8266com_index.template.json

@@ -62,6 +62,9 @@ build.spiffs_start=
 build.spiffs_end=
 build.spiffs_blocksize=
 
+# soft float location
+build.iramfloat=-DFP_IN_IROM
+
 # Fully qualified file names for processing sketch global options
 globals.h.source.fqfn={build.source.path}/{build.project_name}.globals.h
 commonhfile.fqfn={build.core.path}/CommonHFile.h
@@ -79,7 +82,7 @@ compiler.cpreprocessor.flags=-D__ets__ -DICACHE_FLASH -U__STRICT_ANSI__ -D_GNU_S
 compiler.libraries.ldflags=
 
 compiler.c.cmd=xtensa-lx106-elf-gcc
-compiler.c.flags=-c "{compiler.warning_flags}-cflags" -std=gnu17 {build.stacksmash_flags} -g -free -fipa-pta -Werror=return-type -Wpointer-arith -Wno-implicit-function-declaration -Wl,-EL -fno-inline-functions -nostdlib -mlongcalls -mtext-section-literals -falign-functions=4 -MMD -ffunction-sections -fdata-sections {build.exception_flags} {build.sslflags} {build.mmuflags} {build.non32xferflags}
+compiler.c.flags=-c "{compiler.warning_flags}-cflags" -std=gnu17 {build.stacksmash_flags} -g -free -fipa-pta -Werror=return-type -Wpointer-arith -Wno-implicit-function-declaration -Wl,-EL -fno-inline-functions -nostdlib -mlongcalls -mtext-section-literals -falign-functions=4 -MMD -ffunction-sections -fdata-sections {build.exception_flags} {build.sslflags} {build.mmuflags} {build.non32xferflags} {build.iramfloat}
 
 compiler.S.cmd=xtensa-lx106-elf-gcc
 compiler.S.flags=-c -g -x assembler-with-cpp -MMD -mlongcalls "-I{runtime.tools.xtensa-lx106-elf-gcc.path}/include/"
@@ -90,7 +93,7 @@ compiler.c.elf.cmd=xtensa-lx106-elf-gcc
 compiler.c.elf.libs=-lhal -lphy -lpp -lnet80211 {build.lwip_lib} -lwpa -lcrypto -lmain -lwps -lbearssl -lespnow -lsmartconfig -lairkiss -lwpa2 {build.stdcpp_lib} -lm -lc -lgcc
 
 compiler.cpp.cmd=xtensa-lx106-elf-g++
-compiler.cpp.flags=-c "{compiler.warning_flags}-cppflags" {build.stacksmash_flags} -g -free -fipa-pta -Werror=return-type -mlongcalls -mtext-section-literals -fno-rtti -falign-functions=4 {build.stdcpp_level} -MMD -ffunction-sections -fdata-sections {build.exception_flags} {build.sslflags} {build.mmuflags} {build.non32xferflags}
+compiler.cpp.flags=-c "{compiler.warning_flags}-cppflags" {build.stacksmash_flags} -g -free -fipa-pta -Werror=return-type -mlongcalls -mtext-section-literals -fno-rtti -falign-functions=4 {build.stdcpp_level} -MMD -ffunction-sections -fdata-sections {build.exception_flags} {build.sslflags} {build.mmuflags} {build.non32xferflags} {build.iramfloat}
 
 compiler.as.cmd=xtensa-lx106-elf-as
 
@@ -128,7 +131,7 @@ recipe.hooks.prebuild.2.pattern="{runtime.tools.python3.path}/python3" -I "{runt
 recipe.hooks.linking.prelink.1.pattern="{runtime.tools.python3.path}/python3" -I "{runtime.tools.mkdir}" -p "{build.path}/ld_h/"
 recipe.hooks.linking.prelink.2.pattern="{runtime.tools.python3.path}/python3" -I "{runtime.tools.cp}" "{runtime.platform.path}/tools/sdk/ld/{build.flash_ld}" "{build.path}/ld_h/local.eagle.flash.ld.h"
 recipe.hooks.linking.prelink.3.pattern="{compiler.path}{compiler.c.cmd}" -CC -E -P {build.vtable_flags} {build.mmuflags} "{build.path}/ld_h/local.eagle.flash.ld.h" -o "{build.path}/local.eagle.flash.ld"
-recipe.hooks.linking.prelink.4.pattern="{compiler.path}{compiler.c.cmd}" -CC -E -P {build.vtable_flags} {build.mmuflags} "{runtime.platform.path}/tools/sdk/ld/eagle.app.v6.common.ld.h" -o "{build.path}/local.eagle.app.v6.common.ld"
+recipe.hooks.linking.prelink.4.pattern="{compiler.path}{compiler.c.cmd}" {build.iramfloat} -CC -E -P {build.vtable_flags} {build.mmuflags} "{runtime.platform.path}/tools/sdk/ld/eagle.app.v6.common.ld.h" -o "{build.path}/local.eagle.app.v6.common.ld"
 
 ## Compile c files
 recipe.c.o.pattern="{compiler.path}{compiler.c.cmd}" {compiler.cpreprocessor.flags} {compiler.c.flags} -D{build.sdk}=1 -DF_CPU={build.f_cpu} {build.lwip_flags} {build.debug_port} {build.debug_level} -DARDUINO={runtime.ide.version} -DARDUINO_{build.board} -DARDUINO_ARCH_{build.arch} -DARDUINO_BOARD="{build.board}" -DARDUINO_BOARD_ID="{_id}" {build.led} {build.flash_flags} {compiler.c.extra_flags} {build.extra_flags} {includes} "{source_file}" -o "{object_file}"

platform.txt

@@ -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/boards.txt.py

@@ -275,17 +275,23 @@ def scons_patched_match_splitext(path, suffixes=None):
 #
 
 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
 #
@@ -363,17 +369,17 @@ def scons_patched_match_splitext(path, suffixes=None):
     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(
                 [
                     "-D%s=%s" % f if isinstance(f, (tuple, list)) else "-D" + f
                     for f in mmu_flags
                 ]
             ),
-            fp_in_irom,
         ),
         "Generating LD script $TARGET",
     ),

tools/platformio-build.py

@@ -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)