屏蔽和修改来自 FPGA 串行通信的 8 字节信号

Mask and modify 8-byte signal from FPGA serial communication

我很难创建一个掩码来只写入我的数据的某些位。 目前我通过串口读取 32 位数据。阅读后我得到以下信息:

b'rt 00000000\n'

这有字节类型。我假设,我来自某个寄存器的 32 位被转换为 8 个字节。然而,这个寄存器有多个字段,比如说 field1 的范围从 bit 0 到 4,field2 的范围从 bit 4 到 5,field3 的范围从 bit 5 到 8 等等,所以它们在数量、长度和位置上有所不同,具体取决于寄存器。现在我想读取信息,在某个字段上应用掩码,修改该字段,然后将信息写回我的串行设备。我已经编写了额外的函数来获取字段数、字段偏移量和字段宽度的信息。 到目前为止我取得的成就:

    read_value = read_register_byte(s, r, regName) #output: '00000000'
    #from hex to int
    read_value = int(read_value, 16)
    #from int to 32bit-bin without prefix
    read_value = format(read_value, '032b')

    #define mask range
    maskStart = len(read_value) - (offsets[fieldNo] + widths[fieldNo]) #for field0 this results in 28
    maskStop = len(read_value) - offsets[fieldNo] #this results in 32

    #create mask template (32bit)
    mask = [0]*32
    j = 0
    #insert F for mask range
    for i in read_value:
        mask[j] = read_value[j]
        if j >= maskStart and j < maskStop:
            mask[j]='F'
        j+=1
    #to string
    tempMask=""
    for i in mask:
        tempMask += i
    mask = tempMask
read_value
Out[96]: '00000000000000000000000000000000'

mask
Out[97]: '0000000000000000000000000000FFFF'

我想做的是只允许修改那些标有 F 的位。我确信这是非常糟糕的做法,但是如果我只能实现以下步骤,它应该可以工作:使用 read_value 操作我的掩码,将我的数据转换回 8 字节格式并写入我的串行设备。

编辑:

Field = namedtuple("Field", ["pos_lsb", "width"])
REG_WIDTH = 32 #r.width
REG_HEX_DIGITS = REG_WIDTH // 4

def create_mask(pos_lsb, width):
    mask = ((1 << width)-1) << pos_lsb
    return mask

def get_field(reg_value, field):
    mask = create_mask(*field)
    field_value = (reg_value & mask) >> field.pos_lsb
    return field_value

def set_field(reg_value, field, new_value):
    mask = create_mask(*field)
    reg_value = (reg_value & ~mask) | (new_value << field.pos_lsb)
    return reg_value

def value_from_string(reg_value_string):
    return int(reg_value_string, 16)

def value_to_string(reg_value):
    return f"{reg_value:0{REG_HEX_DIGITS}X}"

def write_field(s, r, regName, fieldNo, data):
    """ Writes to a single field of a Trixel register """
    """ debug block """
    # s = open_serial_port()
    # r = Registermap()
    # regName = 'tcm_control'
    # fieldNo = 0 #1st field
    # data = 5
    """ end of debug block """

    regAddress = r.get_register_address(regName)
    fields = r.get_register(regName, 'fields')
    offsets = r.get_register(regName, 'offsets')
    widths = r.get_register(regName, 'widths')

    if fieldNo+1 > fields:
        print('fieldNo out of range (max fields: ' + str(fields) + '). Aborting..')
        return 0

    fieldStart = r.baseAddress + regAddress + offsets[fieldNo]
    addr = r.baseAddress + regAddress
    register_value_string = read_register_byte(s, r, regName)
    field = Field(pos_lsb=offsets[fieldNo], width=widths[fieldNo])
    new_field_value = data

    # Update field
    print("Register: " + str(regName) + ", fieldNo: " + str(fieldNo+1) + "(" + str(fieldNo) + ")" + ", offset (hex): " + hex(fieldStart))
    print("Fieldname: " + str(r.get_register(regName,'descriptions')[fieldNo]))
    print(f"Original register value: {register_value_string}")
    reg_val = value_from_string(register_value_string)
    field_value = get_field(reg_val, field)
    print(f"Original field value: {field_value} (0x{field_value:x} in hex)")
    print(f"Setting field to {new_field_value} (0x{new_field_value:x} in hex)")
    reg_val = set_field(reg_val, field, new_field_value)
    field_value = get_field(reg_val, field)
    print(f"New field value: {field_value} (0x{field_value:x} in hex)")
    new_reg_val_string = value_to_string(reg_val)
    print(f"New register value to write to FPGA: {new_reg_val_string}")

    #write to FPGA
    cmd = ("mwr {:08X}".format(addr) + " " + new_reg_val_string + " \n").encode()
    message = s.write(cmd)

    if message != len(cmd):
        print('Error in Write! Bytes expected: ' + str(len(cmd)) + ', written: ' + str(message) + ', cmd: ' + str(cmd))
    elif message == len(cmd):
        print('Write to register ' + str(hex(addr)) + ' OK.')

工作示例:

write_field(s, r, 'tcm_control', 3, 1)
Register: tcm_control, fieldNo: 4(3), offset (hex): 0x50000406
Fieldname: Should be released after configuring all TCM registers over AXI
Original register value: 00000071
Original field value: 1 (0x1 in hex)
Setting field to 1 (0x1 in hex)
New field value: 1 (0x1 in hex)
New register value to write to FPGA: 00000071
Write to register 0x50000400 OK.

失败示例:

write_field(s, r, 'tcm_control', 3, 2)
Register: tcm_control, fieldNo: 4(3), offset (hex): 0x50000406
Fieldname: Should be released after configuring all TCM registers over AXI
Original register value: 00000071
Original field value: 1 (0x1 in hex)
Setting field to 2 (0x2 in hex)
New field value: 0 (0x0 in hex)
New register value to write to FPGA: 000000B1
Write to register 0x50000400 OK.

read_register_byte(s, r, 'tcm_control')
Out[15]: '00000031'

我认为您的处理方式有误。请查看这段(评论不多的)代码,看看这是否是您真正想要的:

from collections import namedtuple

REG_WIDTH = 32
REG_HEX_DIGITS = REG_WIDTH // 4


Field = namedtuple("Field", ["pos_lsb", "width"])


def create_mask(pos_lsb, width):
    mask = ((1 << width)-1) << pos_lsb
    return mask


def get_field(reg_value, field):
    mask = create_mask(*field)
    field_value = (reg_value & mask) >> field.pos_lsb
    return field_value


def set_field(reg_value, field, new_value):
    mask = create_mask(*field)
    reg_value = (reg_value & ~mask) | (new_value << field.pos_lsb)
    return reg_value


def value_from_string(reg_value_string):
    return int(reg_value_string, 16)


def value_to_string(reg_value):
    return f"{reg_value:0{REG_HEX_DIGITS}X}"


register_value_string = "0F00F0FF"
field1 = Field(pos_lsb=3, width=5)
new_field_value = 0x12

# Update field1.
print(f"Original register value: {register_value_string}")
reg_val = value_from_string(register_value_string)
field_value = get_field(reg_val, field1)
print(f"Original field value: {field_value} (0x{field_value:x} in hex)")
print(f"Setting field to {new_field_value} (0x{new_field_value:x} in hex)")
reg_val = set_field(reg_val, field1, new_field_value)
field_value = get_field(reg_val, field1)
print(f"New field value: {field_value} (0x{field_value:x} in hex)")
new_reg_val_string = value_to_string(reg_val)
print(f"New register value to write to FPGA: {new_reg_val_string}")

输出:

Original register value: 0F00F0FF
Original field value: 31 (0x1f in hex)
Setting field to 18 (0x12 in hex)
New field value: 18 (0x12 in hex)
New register value to write to FPGA: 0F00F097

我相信这更符合您的要求。如果你想让我进一步解释,请告诉我。