src/graphics/lib/magma/include/virtio/virtio_magma_h_gen.py

#!/usr/bin/env fuchsia-vendored-python
# Copyright 2019 The Fuchsia Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

import json
import sys


def usage():
    print(
        "Usage:\n"
        "  virtio_magma_h_gen.py FORMAT INPUT OUTPUT\n"
        '    FORMAT   either "fuchsia" or "linux"\n'
        "    INPUT    json file containing the magma interface definition\n"
        "    OUTPUT   destination path for the virtio header file to generate\n"
        "  Example: ./virtio_magma_h_gen.py fuchsia ../magma/magma.json ./virtio_magma.h\n"
        "  Generates the virtio magma header based on a provided json definition,\n"
        "  for either fuchsia or the linux kernel."
    )


# Generates a c or cpp style comment
def comment(lines, cpp):
    ret = [f"// {lines[0]}\n" if cpp else f"/* {lines[0]}\n"]
    if cpp:
        ret.extend(f"// {line}\n" for line in lines[1:])
    else:
        ret.extend(f"   {line}\n" for line in lines[1:])
        ret.append(" */\n")
    return "".join(ret)


# Wire formats for various widths
def wire_format_from_width(width):
    global fuchsia
    global tab
    format_fuchsia = {
        1: "uint8_t",
        2: "uint16_t",
        4: "uint32_t",
        8: "uint64_t",
    }
    format_linux = {
        1: "u8",
        2: "__le16",
        4: "__le32",
        8: "__le64",
    }
    invalid = "INVALID TYPE WIDTH"
    if fuchsia:
        return format_fuchsia.get(width, invalid)
    return format_linux.get(width, invalid)


def wire_width(type):
    # Default to 8 bytes
    width = 8
    if type == "uint64_t":
        width = 8
    if type == "uint32_t":
        width = 4
    if type == "int32_t":
        width = 4
    if type == "magma_bool_t":
        width = 1
    if type == "magma_handle_t":
        width = 4
    if type.find("magma_image_info_t") != -1:
        width = 0  # Unknown
    if type.find("magma_buffer_info_t") != -1:
        width = 0  # Unknown
    return width


# Wire format for a given type
def wire_format(type):
    if type.find("*") != -1:
        return wire_format_from_width(8)
    return wire_format_from_width(wire_width(type))


# License string for the top of the file.
def license():
    global fuchsia
    lines = [
        "Copyright 2018 The Fuchsia Authors. All rights reserved.",
        "Use of this source code is governed by a BSD-style license that can be",
        "found in the LICENSE file.",
    ]
    return comment(lines, fuchsia)


# Warning string about auto-generation
def warning():
    global fuchsia
    lines = [
        "NOTE: DO NOT EDIT THIS FILE! It is generated automatically by:",
        "  //src/graphics/lib/magma/include/virtio/virtio_magma_h_gen.py",
    ]
    return comment(lines, fuchsia)


# Guard macro that goes at the beginning/end of the header (after license).
def guards(begin):
    global fuchsia
    global tab
    macro = "_LINUX_VIRTIO_MAGMA_H"
    if fuchsia:
        macro = "SRC_GRAPHICS_LIB_MAGMA_INCLUDE_VIRTIO_VIRTIO_MAGMA_H_"
    if begin:
        return "#ifndef " + macro + "\n#define " + macro + "\n"
    return "#endif " + comment([macro], fuchsia)


# Includes lists.
def includes():
    if fuchsia:
        return "#include <stdint.h>\n" "#include <zircon/compiler.h>\n"
    else:
        return (
            "#include <linux/virtio_ids.h>\n"
            "#include <linux/virtio_config.h>\n"
        )


# Extract the non-"magma_" portion of the name of an export
def get_name(export):
    return export["name"][len("magma_") :]


# Generate a 4-digit hex string for a given integer, checking against collisions
def format_id(id, used):
    ret = "0x{:04X}".format(id)
    if id > len(used) or used[id]:
        raise Exception("Command ID collision: " + ret)
    used[id] = True
    return ret


# Generate enum
def gen_enums(magma):
    global fuchsia
    global tab
    commands = tab + comment(["magma commands"], fuchsia)
    responses = tab + comment(["magma success responses"], fuchsia)
    errors = tab + comment(["magma error responses"], fuchsia)
    string_table = "inline const char* virtio_magma_ctrl_type_string(enum virtio_magma_ctrl_type type) {\n"
    string_table += tab + "switch (type) {\n"
    expected_response_table = "inline enum virtio_magma_ctrl_type virtio_magma_expected_response_type(enum virtio_magma_ctrl_type type) {\n"
    expected_response_table += tab + "switch (type) {\n"
    command_id_base = 0x1000
    response_id_base = 0x2000
    error_id_base = 0x3000
    max_id_count = 0x4000
    used = [False] * max_id_count
    for method in magma["exports"] + magma["virtmagma-internal"]:
        name = get_name(method).upper()
        ordinal = method["ordinal"]
        assert ordinal < magma["next-free-ordinal"]
        command_id = command_id_base + ordinal
        response_id = response_id_base + ordinal
        commands += (
            tab
            + "VIRTIO_MAGMA_CMD_"
            + name
            + " = "
            + format_id(command_id, used)
            + ",\n"
        )
        responses += (
            tab
            + "VIRTIO_MAGMA_RESP_"
            + name
            + " = "
            + format_id(response_id, used)
            + ",\n"
        )
        command_id = response_id = ""
        string_table += (
            tab
            + tab
            + "case VIRTIO_MAGMA_CMD_"
            + name
            + ': return "VIRTIO_MAGMA_CMD_'
            + name
            + '";\n'
        )
        string_table += (
            tab
            + tab
            + "case VIRTIO_MAGMA_RESP_"
            + name
            + ': return "VIRTIO_MAGMA_RESP_'
            + name
            + '";\n'
        )
        expected_response_table += (
            tab
            + tab
            + "case VIRTIO_MAGMA_CMD_"
            + name
            + ": return VIRTIO_MAGMA_RESP_"
            + name
            + ";\n"
        )
    error_names = [
        "VIRTIO_MAGMA_RESP_ERR_UNIMPLEMENTED",
        "VIRTIO_MAGMA_RESP_ERR_INTERNAL",
        "VIRTIO_MAGMA_RESP_ERR_HOST_DISCONNECTED",
        "VIRTIO_MAGMA_RESP_ERR_OUT_OF_MEMORY",
        "VIRTIO_MAGMA_RESP_ERR_INVALID_COMMAND",
        "VIRTIO_MAGMA_RESP_ERR_INVALID_ARGUMENT",
    ]
    error_id = error_id_base + 1
    for error_name in error_names:
        errors += tab + error_name + " = " + format_id(error_id, used) + ",\n"
        string_table += (
            tab
            + tab
            + "case "
            + error_name
            + ': return "'
            + error_name
            + '";\n'
        )
        error_id = error_id + 1
    string_table += (
        tab + tab + 'default: return "[invalid virtio_magma_ctrl_type]";\n'
    )
    string_table += tab + "}\n"
    string_table += "}\n"
    expected_response_table += (
        tab + tab + "default: return VIRTIO_MAGMA_RESP_ERR_INVALID_COMMAND;\n"
    )
    expected_response_table += tab + "}\n"
    expected_response_table += "}\n"
    ret = "enum virtio_magma_ctrl_type {\n"
    ret += commands
    ret += responses
    ret += errors
    if fuchsia:
        ret += "} __PACKED;\n\n"
    else:
        ret += "} __attribute((packed));\n\n"
    ret += string_table + "\n"
    ret += expected_response_table
    return ret


def is_request_argument(argument):
    # Out params with unknown sizes are kept in the request struct
    # because response struct elements must be 8 bytes.
    if argument["name"].find("_out") == -1 or wire_width(argument["type"]) == 0:
        return True
    return False


# Format command or response struct for an export
def format_struct(export, ctrl):
    global fuchsia
    global tab
    name = (
        "virtio_magma_" + get_name(export) + "_" + ("ctrl" if ctrl else "resp")
    )
    ret = ""
    ret += "typedef "
    ret += "struct " + name + " {\n"
    ret += tab + "virtio_magma_ctrl_hdr_t hdr;\n"
    for argument in export["arguments"]:
        # Include this argument iff out and resp or !out and ctrl
        use = False
        if is_request_argument(argument):
            if ctrl:
                use = True
        else:
            if not ctrl:
                use = True
        if use:
            ret += (
                tab
                + wire_format(argument["type"])
                + " "
                + argument["name"]
                + ";\n"
            )
    # Add return value, if any
    if not ctrl:
        if export["type"] != "void":
            ret += tab + wire_format(export["type"]) + " result_return;\n"
    if fuchsia:
        ret += "} __PACKED " + name + "_t;\n"
    else:
        ret += "} __attribute((packed)) " + name + "_t;\n"
    return ret


def config_type():
    global fuchsia
    global tab
    ret = ""
    ret += "typedef "
    ret += "struct virtio_magma_config {\n"
    ret += tab + wire_format("uint64_t") + " dummy;\n"
    if fuchsia:
        ret += "} __PACKED virtio_magma_config_t;\n"
    else:
        ret += "} __attribute((packed)) virtio_magma_config_t;\n"
    return ret


# Common control header struct
def ctrl_hdr():
    global fuchsia
    global tab
    ret = ""
    ret += "typedef "
    ret += "struct virtio_magma_ctrl_hdr {\n"
    ret += tab + wire_format("uint32_t") + " type;\n"
    ret += tab + wire_format("uint32_t") + " flags;\n"
    if fuchsia:
        ret += "} __PACKED virtio_magma_ctrl_hdr_t;\n"
    else:
        ret += "} __attribute((packed)) virtio_magma_ctrl_hdr_t;\n"
    return ret


fuchsia = True
tab = "    "


def main():
    global fuchsia
    global tab
    if len(sys.argv) != 4:
        usage()
        return 2
    if sys.argv[1] == "linux":
        fuchsia = False
        tab = "\t"
    elif sys.argv[1] != "fuchsia":
        usage()
        return 2
    with open(sys.argv[2], "r") as file:
        with open(sys.argv[3], "w") as dest:
            magma = json.load(file)["magma-interface"]
            header = license() + "\n"
            header += warning() + "\n"
            header += guards(True) + "\n"
            header += includes() + "\n"
            if fuchsia:
                header += "__BEGIN_CDECLS\n\n"
            header += config_type() + "\n"
            header += gen_enums(magma) + "\n"
            header += ctrl_hdr() + "\n"
            for method in magma["exports"] + magma["virtmagma-internal"]:
                header += format_struct(method, True) + "\n"
                header += format_struct(method, False) + "\n"
            if fuchsia:
                header += "__END_CDECLS\n\n"
            header += guards(False)
            dest.write(header)


if __name__ == "__main__":
    sys.exit(main())