Add AVR support

This requires support in LLVM, as AVR support is still experimental. For
example, in bindings/go/build.sh, add
-DLLVM_EXPERIMENTAL_TARGETS_TO_BUILD=AVR to cmake_flags.

gen-device.py

@@ -143,6 +143,110 @@ def parseSVDRegister(peripheralName, regEl, baseAddress, namePrefix=''):
         'array':       array,
     }
 
+def readATDF(path):
+    # Read Atmel device descriptor files.
+    # See: http://packs.download.atmel.com
+
+    device = Device()
+
+    xml = minidom.parse(path)
+    device = xml.getElementsByTagName('device')[0]
+    deviceName = device.getAttribute('name')
+    arch = device.getAttribute('architecture')
+    family = device.getAttribute('family')
+
+    memorySizes = {}
+    for el in device.getElementsByTagName('address-space'):
+        addressSpace = {
+            'size': int(el.getAttribute('size'), 0),
+            'segments': {},
+        }
+        memorySizes[el.getAttribute('name')] = addressSpace
+        for segmentEl in el.getElementsByTagName('memory-segment'):
+            addressSpace['segments'][segmentEl.getAttribute('name')] = int(segmentEl.getAttribute('size'), 0)
+
+    device.interrupts = []
+    for el in device.getElementsByTagName('interrupts')[0].getElementsByTagName('interrupt'):
+        device.interrupts.append({
+            'index':       int(el.getAttribute('index')),
+            'name':        el.getAttribute('name'),
+            'description': el.getAttribute('caption'),
+        })
+
+    allRegisters = {}
+    commonRegisters = {}
+
+    device.peripherals = []
+    for el in xml.getElementsByTagName('modules')[0].getElementsByTagName('module'):
+        peripheral = {
+            'name':        el.getAttribute('name'),
+            'description': el.getAttribute('caption'),
+            'registers':   [],
+        }
+        device.peripherals.append(peripheral)
+        for regElGroup in el.getElementsByTagName('register-group'):
+            for regEl in regElGroup.getElementsByTagName('register'):
+                size = int(regEl.getAttribute('size'))
+                regName = regEl.getAttribute('name')
+                regOffset = int(regEl.getAttribute('offset'), 0)
+                reg = {
+                    'description': regEl.getAttribute('caption'),
+                    'bitfields':   [],
+                    'array':       None,
+                }
+                if size == 1:
+                    reg['variants'] = [{
+                        'name':    regName,
+                        'address': regOffset,
+                    }]
+                elif size == 2:
+                    reg['variants'] = [{
+                        'name':    regName + 'L',
+                        'address': regOffset,
+                    }, {
+                        'name':    regName + 'H',
+                        'address': regOffset,
+                    }]
+                else:
+                    reg['variants'] = [] # TODO
+
+                for bitfieldEl in regEl.getElementsByTagName('bitfield'):
+                    reg['bitfields'].append({
+                        'name':        regName + '_' + bitfieldEl.getAttribute('name'),
+                        'description': bitfieldEl.getAttribute('caption'),
+                        'value':       int(bitfieldEl.getAttribute('mask'), 0),
+                    })
+
+                if regName in allRegisters:
+                    firstReg = allRegisters[regName]
+                    if firstReg['register'] in firstReg['peripheral']['registers']:
+                        firstReg['peripheral']['registers'].remove(firstReg['register'])
+                    if firstReg['address'] != regOffset:
+                        continue # TODO
+                    commonRegisters = allRegisters[regName]['register']
+                    continue
+                else:
+                    allRegisters[regName] = {'address': regOffset, 'register': reg, 'peripheral': peripheral}
+
+                peripheral['registers'].append(reg)
+
+    device.metadata = {
+        'file':             os.path.basename(path),
+        'descriptorSource': 'http://packs.download.atmel.com/',
+        'name':             deviceName,
+        'nameLower':        deviceName.lower(),
+        'description':      'Device information for the {}.'.format(deviceName),
+        'licenseBlock':     '',
+        'regType':          'uint8',
+        'arch':             arch,
+        'family':           family,
+        'flashSize':        memorySizes['prog']['size'],
+        'ramSize':          memorySizes['data']['segments'].get('IRAM', memorySizes['data']['segments'].get('INTERNAL_SRAM')),
+        'numInterrupts':    len(device.interrupts),
+    }
+
+    return device
+
 def writeGo(outdir, device):
     # The Go module for this device.
     out = open(outdir + '/' + device.metadata['nameLower'] + '.go', 'w')
@@ -224,6 +328,19 @@ const (
                 out.write('\n')
         out.write(')\n')
 
+def writeLD(outdir, device):
+    # Variables for the linker script.
+    out = open(outdir + '/' + device.metadata['nameLower'] + '.ld', 'w')
+    out.write('''\
+/* Automatically generated file. DO NOT EDIT. */
+/* Generated by gen-device.py from {file}, see {descriptorSource} */
+
+__flash_size = 0x{flashSize:x};
+__ram_size   = 0x{ramSize:x};
+__num_isrs   = {numInterrupts};
+'''.format(**device.metadata))
+    out.close()
+
 
 def generate(indir, outdir):
     for filepath in glob(indir + '/*.svd'):
@@ -231,8 +348,14 @@ def generate(indir, outdir):
         device = readSVD(filepath)
         writeGo(outdir, device)
 
+    for filepath in glob(indir + '/*.atdf'):
+        print(filepath)
+        device = readATDF(filepath)
+        writeGo(outdir, device)
+        writeLD(outdir, device)
+
 
 if __name__ == '__main__':
-    indir = sys.argv[1] # directory with register descriptor files (*.svd)
+    indir = sys.argv[1] # directory with register descriptor files (*.svd, *.atdf)
     outdir = sys.argv[2] # output directory
     generate(indir, outdir)