improved elf loading

cfg/chconf.h

@@ -751,6 +751,9 @@
 /* Port-specific settings (override port settings defaulted in chcore.h).    */
 /*===========================================================================*/
 
+// Enable syscall support
+#define PORT_USE_SYSCALL                    TRUE
+
 #endif  /* CHCONF_H */
 
 /** @} */

gui/wxmain.cpp

@@ -181,18 +181,13 @@ void MainFrame::prepareEditor()
 
 static const char *makefile_text = R"make(
 all:
-	@arm-none-eabi-g++ -x c++ -mcpu=cortex-m4 -mthumb -Os --specs=nosys.specs -nostartfiles -fPIE -c $0 -o $0.o
-	@arm-none-eabi-ld -shared -n -N -z max-page-size=512 -Ttext-segment=0 \
-	    $0.o -o $0.so
-	@arm-none-eabi-strip -s -S --strip-unneeded $0.so
-	@arm-none-eabi-objcopy --remove-section .dynsym \
-						   --remove-section .dynstr \
-						   --remove-section .dynamic \
-						   --remove-section .hash \
-						   --remove-section .ARM.exidx \
-						   --remove-section .ARM.attributes \
-						   --remove-section .comment \
-						   $0.so
+	@arm-none-eabi-g++ -x c++ -mcpu=cortex-m4 -mthumb -Os --specs=nosys.specs -nostartfiles -fPIE $0 -o $0.o -Wl,-Ttext-segment=0 -Wl,-eprocess_data_entry -Wl,-zmax-page-size=512
+	@arm-none-eabi-strip -s -S --strip-unneeded $0.o
+	@arm-none-eabi-objcopy --remove-section .ARM.exidx \
+                           --remove-section .ARM.attributes \
+                           --remove-section .comment \
+                           --remove-section .noinit \
+                           $0.o
 )make";
 
 static const char *file_header = R"cpp(
@@ -200,10 +195,21 @@ static const char *file_header = R"cpp(
 
 using adcsample_t = uint16_t;
 
-__attribute__((section(".process_data"))) void process_data(adcsample_t *samples, unsigned int size);
+static void process_data(adcsample_t *samples, unsigned int size);
 
-// End stmdspgui header code
+__attribute__((optimize("-O0")))
+static void *alloc(unsigned int count) {
+    void *result = nullptr;
+    asm("mov r0, %0; mov r1, %1; svc 0" :: "r" (&result), "r" (count));
+    return result;
+}
 
+extern "C" void process_data_entry() {
+    auto func = (void (*)())process_data;
+    func();
+}
+
+// End stmdspgui header code
 )cpp";
 
 wxString MainFrame::compileEditorCode()
@@ -223,7 +229,7 @@ wxString MainFrame::compileEditorCode()
     wxString make_command = wxString("make -C ") + file_name.BeforeLast('/') +
                             " -f " + file_name + "make";
     if (system(make_command.ToAscii()) == 0)
-        return file_name + ".so";
+        return file_name + ".o";
     else
         return "";
 }

source/elf_load.cpp

@@ -54,29 +54,25 @@ entry_t load(void *elf_data, void *elf_load_offset)
     //                  [elf_load_offset](auto func) { (func + elf_load_offset)(); });
     //}
 
-    // Find filter code start
-    if (auto filter = find_section(ehdr, ".process_data"); filter)
-        return ptr_from_offset<entry_t>(elf_load_offset, filter->sh_addr | 1); // OR 1 to enable thumb
-    else
-        return nullptr;
+    return ptr_from_offset<entry_t>(elf_load_offset, ehdr->e_entry);
 }
 
 } // namespace elf
 
 Elf32_Shdr *find_section(Elf32_Ehdr *ehdr, const char *name)
 {
-	auto shdr = ptr_from_offset<Elf32_Shdr *>(ehdr, ehdr->e_shoff);
-	auto shdr_str = ptr_from_offset<Elf32_Shdr *>(ehdr,
+    auto shdr = ptr_from_offset<Elf32_Shdr *>(ehdr, ehdr->e_shoff);
+    auto shdr_str = ptr_from_offset<Elf32_Shdr *>(ehdr,
         ehdr->e_shoff + ehdr->e_shstrndx * ehdr->e_shentsize);
 
-	for (Elf32_Half i = 0; i < ehdr->e_shnum; i++) {
-		char *section = ptr_from_offset<char *>(ehdr, shdr_str->sh_offset) + shdr->sh_name;
-		if (!strcmp(section, name))
-			return shdr;
+    for (Elf32_Half i = 0; i < ehdr->e_shnum; i++) {
+        char *section = ptr_from_offset<char *>(ehdr, shdr_str->sh_offset) + shdr->sh_name;
+        if (!strcmp(section, name))
+            return shdr;
 
-		shdr = ptr_from_offset<Elf32_Shdr *>(shdr, ehdr->e_shentsize);
-	}
+        shdr = ptr_from_offset<Elf32_Shdr *>(shdr, ehdr->e_shentsize);
+    }
 
-	return 0;
+    return 0;
 }
 

source/main.cpp

@@ -111,12 +111,52 @@ int main()
 	}
 }
 
+void quick_freeall();
+
 void signal_operate(adcsample_t *buffer, size_t count)
 {
-    if (elf_entry)
+    if (elf_entry) {
         elf_entry(buffer, count);
+        quick_freeall();
+    }
+
     auto dac_buffer = &dac_samples[buffer == &adc_samples[0] ? 0 : 1024];
     std::copy(buffer, buffer + count, dac_buffer);
     signal_operate_done = buffer == &adc_samples[1024];
 }
 
+// Dynamic memory allocation below
+
+uint8_t quick_malloc_heap[8192];
+uint8_t *quick_malloc_next = quick_malloc_heap;
+
+void *quick_malloc(unsigned int size)
+{
+    if (auto free = std::distance(quick_malloc_next, quick_malloc_heap + 8192); free < 0 || size > static_cast<unsigned int>(free))
+        return nullptr;
+
+    auto ptr = quick_malloc_next;
+    quick_malloc_next += size;
+    return ptr;
+}
+
+void quick_freeall()
+{
+    if (quick_malloc_next != quick_malloc_heap)
+        quick_malloc_next = quick_malloc_heap;
+}
+
+void port_syscall(struct port_extctx *ctxp, uint32_t n)
+{
+    switch (n) {
+    case 0:
+        *reinterpret_cast<void **>(ctxp->r0) = quick_malloc(ctxp->r1);
+        break;
+    case 1:
+        quick_freeall();
+        break;
+    }
+
+    chSysHalt("svc");
+}
+