读取二进制文件和结构体对我来说是一个新的领域。
我理解如何在文件中读取并尝试了各种方法来读取原始数据，但似乎我需要使用struct。
我正在尝试将这些指令翻译成python代码:
二进制合并文件的开头包含一个用于各种通道的GWI_file_header_struct结构数组(在INET_INT.H文件中定义)，后面是交错的32位浮点数据。报头中的前4个字节是以字节为单位的1个通道的报头长度(即516 = 0x0204)。要读取文件中存储的通道数，请读取第一个结构体的'channelsPerFile'字段(例如，查看有多少头文件)。在报头之后，数据以隔行形式保存，其中的点按及时获取的顺序存储。
主要的困惑是我如何将其转换为:
struct.unpack(...)
INET_INT.H结构:
typedef struct GWI_file_header_struct{ // This struct is at the beginning of GWI iNet BINARY files that contain waves.
//
// Macintosh:
//
// file type: 'GWID'
// creator type: 'ioNe' NETWORK_DATA_CREATOR
// ----------------------------------
// HEADER INFORMATION
iNetINT32 headerSizeInBytes; // contains length, in bytes, of this header (this does not include any data) { bytes 0..3, base 0 }
// ----------------------------------
// FILE INFORMATION
iNetINT32 int32key; // 32bit key that should contain 0x12345678 (this will help you make sure your byte lanes are ok).
// { bytes 4..7, base 0 }
iNetINT32 file_endian; // endian mode of stored data on disk: 0 = bigEndian_ion, 1 = littleEndian_ion
// { bytes 8..11, base 0 }
iNetINT16 int16key; // 16bit key that should contain 0x55b4; (this field should consume 2 bytes
// in the struct -- no padding) (i.e. INET_INT16_KEY = 0x55b4)
// { bytes 12..13, base 0 }
iNetINT16 zero; // set to 0 (this field should consume 2 bytes in the struct -- no padding)
// { bytes 14..15, base 0 }
// # of seconds since Jan 1, Midnight, 1904 that the acquisition started (this is used to compute the
// date of acquisition). This overflows in 2030.
// Strip Chart: 1st digitized point in entire stream (i.e. 1st pt of 1st scan)
// Osc Mode: 1st point in current scan, secsSince1904_Int64 units
// { bytes 16..19, base 0 }
iNetUINT32 acquisition_SecsSince1904_FixedUint32_OverflowIn2030;
// ----------------------------------
// # OF POINTS STORED
//
// This file contains a set of scans. Each scan is 1 to .5billion points long. For example,
// we might have 100 scans, each 1000 points long. In this example:
//
// pointsPerScanThisChannel_LSW = 1000
// pointsPerScanThisChannel_MSW = 0
//
// numScansStoredBeforeLastScan = 99
//
// numPointsInLastPartialScan_LSW = 1000
// numPointsInLastPartialScan_MSW = 0
//
// Each channel can have a different number of points per scan due to the sampleRateChanMULTiplier
iNetUINT32 pointsPerScanThisChannel_LSW;
iNetUINT32 pointsPerScanThisChannel_MSW;
// # points per scan = (pointsPerScanThisChannel_MSW * 2^32) + pointsPerScanThisChannel_LSW
// { bytes 20..23, base 0 }
// { bytes 24..27, base 0 }
iNetUINT32 numScansStoredBeforeLastScan_LSW;
// # of complete scans stored in file
// { bytes 28..31, base 0 }
// iNetUINT32 numScansStoredBeforeLastScan_MSW;
// this is defined below, at the end of the struct
iNetUINT32 numPointsInLastPartialScan_LSW;
iNetUINT32 numPointsInLastPartialScan_MSW;
// # points stored in last scan if it is partially complete = (numPointsInLastPartialScan_MSW * 2^32) + numPointsInLastPartialScan_LSW
// { bytes 32..35, base 0 }
// { bytes 36..39, base 0 }
// ----------------------------------
// TIME INFORMATION
iNetFLT32 firstPoint_Time_Secs; // time of 1st point, units are seconds
// { bytes 40..43, base 0 }
iNetFLT32 endUser_channel_samplePeriod_Secs;
// time between points for this channel,
// units are seconds. Notice that channels
// can have different sample rates, which
// is the master_endUser_SampleRate / sampleRate_Divider,
// where 'sampleRate_Divider' is an integer.
// { bytes 44..47, base 0 }
// ----------------------------------
// TYPE OF DATA STORED
iNetINT32 arrayDataType; // Type of src array data. iNetDataType:
//
// 0 iNetDT_INT16: 16bit integer, signed
// 2 iNetDT_UINT16: 16bit integer, unsigned
// 3 iNetDT_INT32: 32bit integer, signed
// 4 iNetDT_UINT32: 32bit integer, unsigned
// 5 iNetDT_FLT32: 32bit float (IEEE flt32 format)
// 6 iNetDT_Double: 'double', as determined by the compiler
// (e.g. flt64, flt80, flt96, flt128)
// see 'bytesPerDataPoint' field to see
// how many bytes
// { bytes 48..51, base 0 }
iNetINT32 bytesPerDataPoint; // # of bytes for each datapoint (e.g. 4 for 32bit signed integer)
// { bytes 52..55, base 0 }
iNetStr31 verticalUnitsLabel; // pascal string of vertical units label (e.g. "Volts")
// { bytes 56..87, base 0 }
iNetStr31 horizontalUnitsLabel; // horizontal units label, e.g. "Secs", pascal string (0th char is the # of valid chars)
// { bytes 88..119, base 0 }
iNetStr31 userName; // user named set by user, e.g. "Pressure 1" , pascal string (0th char is the # of valid chars)
// { bytes 120..151, base 0 }
iNetStr31 chanName; // name of channel, e.g. "Ch1 Vin+", pascal string (0th char is the # of valid chars)
// { bytes 152..183, base 0 }
// ----------------------------------
// DATA MAPPING
//
iNetINT32 minCode; // if data is stored in integer format, this contains the mapping from integer
iNetINT32 maxCode; // to engineering units (e.g. +/-2048 A/D data is mapped to +/- 10V, minCode = -2048,
iNetFLT32 minEU; // maxCode = +2047, minEU = -10.000, maxEU = +9.995.
iNetFLT32 maxEU; //
// { bytes 184..187, base 0 }
// { bytes 188..191, base 0 }
// { bytes 192..195, base 0 }
// { bytes 196..199, base 0 }
// ----------------------------------
// iNet NETWORK ADDRESS (this does not need
// to be filled in, 0L's are ok)
iNetINT32 netNum; // channel network # (this pertains to iNet only; use 0 otherwise)
// { bytes 200..203, base 0 }
iNetINT32 devNum; // channel device # (this pertains to iNet only; use 0 otherwise)
// { bytes 204..207, base 0 }
iNetINT32 modNum; // channel module # (this pertains to iNet only; use 0 otherwise)
// { bytes 208..211, base 0 }
iNetINT32 chNum; // channel channel # (this pertains to iNet only; use 0 otherwise)
// { bytes 212..215, base 0 }
// ----------------------------------
// END USER NOTES
iNetStr255 notes; // pascal string that contains notes about the data stored.
// { bytes 216..471, base 0 }
// ----------------------------------
// MAPPING
iNetFLT32 /* must remain flt32 */ internal1; // Mapping from internal engineering units (e.g. Volts) to external engineering
iNetFLT32 /* must remain flt32 */ external1; // units (e.g. mmHg). This is used for 2 point linear mapping/calibration to
iNetFLT32 /* must remain flt32 */ internal2; // a new, user defined, coordinate system. instruNet World does not read these values
iNetFLT32 /* must remain flt32 */ external2; // from the wave files, yet instead reads them from the instrNet.prf file -- they
// are only stored for the benefit of other software that might read this file. gsw 12/1/96
// { bytes 472..475, base 0 }
// { bytes 476..479, base 0 }
// { bytes 480..483, base 0 }
// { bytes 484..487, base 0 }
iNetFLT32 flt32key; // flt32 key set to 1234.56 (i.e. INET_FLT32_KEY), Used to test floating point code. gsw 12/1/96
// { bytes 488..491, base 0 }
iNetINT32 sampleRate_Divider; // this channel is digitized at the master_endUser_SampleRate divided
// this 'sampleRate_Divider' (i.e. sampleRateChanMULT_integerRatio_N_int64)
// (helpful with FileType Binary Merge), gsw 1/29/97. Note: This field was introduced 1/29/97 and
// files saved before that time set it to 0.
// { bytes 492..495, base 0 }
iNetINT32 channelsPerFile; // # of channels per file (i.e. interlaced after array of headers) (helpful with FileType Binary Merge), gsw 1/29/97
// Note: This field was introduced 1/29/97 and files saved before that time set it to 0.
// { bytes 496..499, base 0 }
// ----------------------------------
// EXPANSION FIELDS
#if 1 // gsw 12/23/09
// # of complete scans stored in file, MS 32bits
// { bytes 500..503, base 0 }
iNetUINT32 numScansStoredBeforeLastScan_MSW;
#else
iNetINT32 expansion8; // expansion fields that are preset to
#endif
iNetINT32 expansion9; // 0 and then ignored
iNetINT32 expansion10; // { bytes 500..503, base 0 }
// { bytes 504..507, base 0 }
// { bytes 508..511, base 0 }
// ----------------------------------
// KEY TO TEST STRUCT PACKING
iNetINT32 int32key_StructTest; // 32bit key that should contain 0x12345678; (i.e. INET_INT32_KEY)
// { bytes 512..515, base 0 }
// ----------------------------------
// ACTUAL DATA
/* iNetFLT32 *data[1]; */ // contains array of data of type 'arrayDataType'
} GWI_file_header_struct;
最终代码和结果:
<代码/em>
from struct import *
# Current 3 channels: Ch11 Vin+, Ch13 Vin+ and Ch15 Vin+
# Header info extracted using provided header struct (INET_INT.H)
# After the header, the data is saved in an interlaced form,
# where points are stored in the order that they are acquired in time.
# 3 channels: A[0], B[0], C[0], A[1], B[1], C[1]...
# After header = 516 header size x 3 channels = 1,548 bytes
# Start of data at 1,548 bytes?
with open(file, "rb") as f:
byte = f.read(12)
header_size, int32key, file_endian = unpack('<3i', byte)
# channel name 1
f.seek(152)
chan = f.read(183-152)
chan = struct.unpack("<31s", chan)[0].rstrip(b'x00').lstrip(b't')
# channel name 2
f.seek(152+header_size)
chan2 = f.read(183-152)
chan2 = struct.unpack("<31s", chan2)[0].rstrip(b'x00').lstrip(b't')
print(header_size, int32key, file_endian)
print("channel 1: {}".format(chan))
print("channel 2: {}".format(chan2))
结果
516 305419896 1
channel 1: b'Ch11 Vin+'
channel 2: b'Ch13 Vin+'
好吧，这不是一个完整的答案，但我觉得这里的评论真的很难读。
第一步是读取前12个字节(三个4字节的整数)，并将它们解包，以便我们可以检查端序。我们先试试大端序
from struct import *
with open(file, "rb") as f:
byte = f.read(12)
header_size, int32key, file_endian = unpack('>3i', byte)
我们期望int32key设置为305419896 (= x12345678)。如果我们得到另一个值，那么让我们切换到little-endian，即将我们的unpack格式字符串更改为<3i。