all: generate interrupt vector from .svd file

.gitignore

@@ -2,3 +2,4 @@ build
 src/device/avr/*.go
 src/device/avr/*.ld
 src/device/nrf/*.go
+src/device/nrf/*.s

src/runtime/runtime_nrf.go

@@ -5,18 +5,53 @@ package runtime
 import (
 	"device/arm"
 	"device/nrf"
+	"unsafe"
 )
 
 type timeUnit int64
 
 const tickMicros = 1024 * 32
 
-//go:export _start
-func _start() {
+//go:linkname systemInit SystemInit
+func systemInit()
+
+//go:export Reset_Handler
+func handleReset() {
+	systemInit()
 	main()
 }
 
+//go:extern _sbss
+var _sbss unsafe.Pointer
+
+//go:extern _ebss
+var _ebss unsafe.Pointer
+
+//go:extern _sdata
+var _sdata unsafe.Pointer
+
+//go:extern _sidata
+var _sidata unsafe.Pointer
+
+//go:extern _edata
+var _edata unsafe.Pointer
+
 func preinit() {
+	// Initialize .bss: zero-initialized global variables.
+	ptr := uintptr(unsafe.Pointer(&_sbss))
+	for ptr != uintptr(unsafe.Pointer(&_ebss)) {
+		*(*uint32)(unsafe.Pointer(ptr)) = 0
+		ptr += 4
+	}
+
+	// Initialize .data: global variables initialized from flash.
+	src := uintptr(unsafe.Pointer(&_sidata))
+	dst := uintptr(unsafe.Pointer(&_sdata))
+	for dst != uintptr(unsafe.Pointer(&_edata)) {
+		*(*uint32)(unsafe.Pointer(dst)) = *(*uint32)(unsafe.Pointer(src))
+		dst += 4
+		src += 4
+	}
 }
 
 func postinit() {
@@ -119,7 +154,7 @@ func rtc_sleep(ticks uint32) {
 }
 
 //go:export RTC0_IRQHandler
-func RTC0_IRQHandler() {
+func handleRTC0() {
 	nrf.RTC0.INTENCLR = nrf.RTC0_INTENSET_COMPARE0_Msk
 	nrf.RTC0.EVENTS_COMPARE[0] = 0
 	rtc_wakeup = true

targets/arm.ld

@@ -34,6 +34,8 @@ SECTIONS
         __StackTop = .;
     } >RAM
 
+    _sidata = LOADADDR(.data);
+
     /* This is the initialized data section
     The program executes knowing that the data is in the RAM
     but the loader puts the initial values in the FLASH (inidata).

targets/pca10040.json

@@ -2,7 +2,7 @@
 	"llvm-target": "armv7em-none-eabi",
 	"build-tags": ["nrf", "nrf52", "nrf52832", "js", "wasm"],
 	"linker": "arm-none-eabi-gcc",
-	"pre-link-args": ["-nostdlib", "-nostartfiles", "-mcpu=cortex-m4", "-mthumb", "-T", "targets/arm.ld", "-Wl,--gc-sections", "-fno-exceptions", "-fno-unwind-tables", "-ffunction-sections", "-fdata-sections", "-Os", "-DNRF52832_XXAA", "-D__STARTUP_CLEAR_BSS", "-Ilib/CMSIS/CMSIS/Include", "lib/nrfx/mdk/gcc_startup_nrf52.S", "lib/nrfx/mdk/system_nrf52.c"],
+	"pre-link-args": ["-nostdlib", "-nostartfiles", "-mcpu=cortex-m4", "-mthumb", "-T", "targets/arm.ld", "-Wl,--gc-sections", "-fno-exceptions", "-fno-unwind-tables", "-ffunction-sections", "-fdata-sections", "-Os", "-DNRF52832_XXAA", "-Ilib/CMSIS/CMSIS/Include", "lib/nrfx/mdk/system_nrf52.c", "src/device/nrf/nrf52.s"],
 	"objcopy": "arm-none-eabi-objcopy",
 	"flash": "nrfjprog -f nrf52 --sectorerase --program {hex} --reset"
 }

tools/gen-device-svd.py

@@ -35,7 +35,7 @@ def readSVD(path):
     xml = minidom.parse(path)
     root = xml.getElementsByTagName('device')[0]
     deviceName = getText(root.getElementsByTagName('name')[0])
-    deviceDescription = getText(root.getElementsByTagName('description')[0])
+    deviceDescription = getText(root.getElementsByTagName('description')[0]).strip()
     licenseText = formatText(getText(root.getElementsByTagName('licenseText')[0]))
     cpu = root.getElementsByTagName('cpu')[0]
     cpuName = getText(cpu.getElementsByTagName('name')[0])
@@ -87,14 +87,16 @@ def readSVD(path):
                 else:
                     continue
 
-    device.interrupts = interrupts.values() # TODO: sort by index
+    device.interrupts = sorted(interrupts.values(), key=lambda v: v['index'])
+    licenseBlock = '//     ' + licenseText.replace('\n', '\n//     ')
+    licenseBlock = '\n'.join(map(str.rstrip, licenseBlock.split('\n'))) # strip trailing whitespace
     device.metadata = {
         'file':             os.path.basename(path),
         'descriptorSource': 'https://github.com/NordicSemiconductor/nrfx/tree/master/mdk',
         'name':             deviceName,
         'nameLower':        deviceName.lower(),
         'description':      deviceDescription,
-        'licenseBlock':     '\n//     ' + licenseText.replace('\n', '\n//     '),
+        'licenseBlock':     licenseBlock,
         'arch':             ARM_ARCHS[cpuName],
         'family':           getText(root.getElementsByTagName('series')[0]),
     }
@@ -164,7 +166,8 @@ def writeGo(outdir, device):
 // +build {pkgName},{nameLower}
 
 // {description}
-// {licenseBlock}
+//
+{licenseBlock}
 package {pkgName}
 
 import "unsafe"
@@ -183,7 +186,7 @@ const (
 )
 '''.format(pkgName=pkgName, **device.metadata))
 
-    out.write('\n// Interrupts\nconst (\n')
+    out.write('\n// Interrupt numbers\nconst (\n')
     for intr in device.interrupts:
         out.write('\tIRQ_{name} = {index} // {description}\n'.format(**intr))
     intrMax = max(map(lambda intr: intr['index'], device.interrupts))
@@ -244,11 +247,89 @@ const (
         out.write(')\n')
 
 
+def writeAsm(outdir, device):
+    # The interrupt vector, which is hard to write directly in Go.
+    out = open(outdir + '/' + device.metadata['nameLower'] + '.s', 'w')
+    out.write('''\
+// Automatically generated file. DO NOT EDIT.
+// Generated by gen-device.py from {file}, see {descriptorSource}
+
+// {description}
+//
+{licenseBlock}
+
+.syntax unified
+
+// This is the default handler for interrupts, if triggered but not defined.
+.section .text.Default_Handler
+.global  Default_Handler
+.type    Default_Handler, %function
+Default_Handler:
+    wfe
+    b    Default_Handler
+
+// Avoid the need for repeated .weak and .set instructions.
+.macro IRQ handler
+.weak  \\handler
+.set   \\handler, Default_Handler
+.endm
+
+.section .isr_vector
+.global  __isr_vector
+    // Interrupt vector as defined by Cortex-M, starting with the stack top.
+    // On reset, SP is initialized with *0x0 and PC is loaded with *0x4, loading
+    // __StackTop and Reset_Handler.
+    .long __StackTop
+    .long Reset_Handler
+    .long NMI_Handler
+    .long HardFault_Handler
+    .long MemoryManagement_Handler
+    .long BusFault_Handler
+    .long UsageFault_Handler
+    .long 0
+    .long 0
+    .long 0
+    .long 0
+    .long SVC_Handler
+    .long DebugMon_Handler
+    .long 0
+    .long PendSV_Handler
+    .long SysTick_Handler
+
+    // Extra interrupts for peripherals defined by the hardware vendor.
+'''.format(**device.metadata))
+    num = 0
+    for intr in device.interrupts:
+        if intr['index'] < num:
+            raise ValueError('interrupt numbers are not sorted or contain a duplicate')
+        while intr['index'] > num:
+            out.write('    .long 0\n')
+            num += 1
+        num += 1
+        out.write('    .long {name}_IRQHandler\n'.format(**intr))
+
+    out.write('''
+    // Define default implementations for interrupts, redirecting to
+    // Default_Handler when not implemented.
+    IRQ NMI_Handler
+    IRQ HardFault_Handler
+    IRQ MemoryManagement_Handler
+    IRQ BusFault_Handler
+    IRQ UsageFault_Handler
+    IRQ SVC_Handler
+    IRQ DebugMon_Handler
+    IRQ PendSV_Handler
+    IRQ SysTick_Handler
+''')
+    for intr in device.interrupts:
+        out.write('    IRQ {name}_IRQHandler\n'.format(**intr))
+
 def generate(indir, outdir):
     for filepath in sorted(glob(indir + '/*.svd')):
         print(filepath)
         device = readSVD(filepath)
         writeGo(outdir, device)
+        writeAsm(outdir, device)
 
 
 if __name__ == '__main__':