can I make Javascript see binary data?
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From: pete on 30 Jul 2010 16:26 Hi everybody -- A friend asks me this question. He is reading mixed ASCII and binary data into his Javascript code. He needs to parse the received record. Some of the binary data are: 1. 16-bit integers 2. 32-bit integers 3. 8-bit integers 4. 32-bit IEEE floats. So I think the question is: can I persuade Javascript to understand and handle 8 arbitrary data bits in an untyped 8-bit byte? If so, then how? Thanks! -- pete
From: Ry Nohryb on 30 Jul 2010 17:52 On Jul 30, 10:26 pm, pete <pete...(a)yahoo.com> wrote: > Hi everybody -- > > A friend asks me this question. He is reading mixed ASCII and binary > data into his Javascript code. He needs to parse the received record. > Some of the binary data are: > > 1. 16-bit integers > 2. 32-bit integers > 3. 8-bit integers > 4. 32-bit IEEE floats. > > So I think the question is: can I persuade Javascript to understand > and handle 8 arbitrary data bits in an untyped 8-bit byte? Not in a browser, no. Not yet. -- Jorge.
From: Denis McMahon on 30 Jul 2010 18:02 On 30/07/10 21:26, pete wrote: > Hi everybody -- > > A friend asks me this question. He is reading mixed ASCII and binary > data into his Javascript code. He needs to parse the received record. > Some of the binary data are: > > 1. 16-bit integers > 2. 32-bit integers > 3. 8-bit integers > 4. 32-bit IEEE floats. > > So I think the question is: can I persuade Javascript to understand > and handle 8 arbitrary data bits in an untyped 8-bit byte? > > If so, then how? bitwise or, bitwise and etc. eg (assuming bit 0 is lsb): if (x & 0x80 == 0x80) alert ("bit 7 is set"); if (x | 0x7f == 0x00) alert ("bit 7 is clear"); x = (x | 0x80); // set bit 7 of x x = (x & 0x7f); // clear bit 7 of x Rgds Denis McMahon
From: pete on 30 Jul 2010 18:27 On Jul 30, 6:02 pm, Denis McMahon <denis.m.f.mcma...(a)googlemail.com> wrote: > On 30/07/10 21:26, pete wrote: > > > Hi everybody -- > > > A friend asks me this question. He is reading mixed ASCII and binary > > data into his Javascript code. He needs to parse the received record. > > Some of the binary data are: > > > 1. 16-bit integers > > 2. 32-bit integers > > 3. 8-bit integers > > 4. 32-bit IEEE floats. > > > So I think the question is: can I persuade Javascript to understand > > and handle 8 arbitrary data bits in an untyped 8-bit byte? > > > If so, then how? > > bitwise or, bitwise and etc. > > eg (assuming bit 0 is lsb): > > if (x & 0x80 == 0x80) alert ("bit 7 is set"); > if (x | 0x7f == 0x00) alert ("bit 7 is clear"); > > x = (x | 0x80); // set bit 7 of x > x = (x & 0x7f); // clear bit 7 of x > > Rgds > > Denis McMahon Right, but also (considering the input stream as an array of bytes): var a = stream[i]; a <<= 8; a += stream[i+1]; -- pete
From: Denis McMahon on 31 Jul 2010 14:21
On 30/07/10 23:27, pete wrote: > On Jul 30, 6:02 pm, Denis McMahon <denis.m.f.mcma...(a)googlemail.com> > wrote: >> On 30/07/10 21:26, pete wrote: >> >>> Hi everybody -- >> >>> A friend asks me this question. He is reading mixed ASCII and binary >>> data into his Javascript code. He needs to parse the received record. >>> Some of the binary data are: >> >>> 1. 16-bit integers >>> 2. 32-bit integers >>> 3. 8-bit integers >>> 4. 32-bit IEEE floats. >> >>> So I think the question is: can I persuade Javascript to understand >>> and handle 8 arbitrary data bits in an untyped 8-bit byte? >> >>> If so, then how? >> >> bitwise or, bitwise and etc. >> >> eg (assuming bit 0 is lsb): >> >> if (x & 0x80 == 0x80) alert ("bit 7 is set"); >> if (x | 0x7f == 0x00) alert ("bit 7 is clear"); >> >> x = (x | 0x80); // set bit 7 of x >> x = (x & 0x7f); // clear bit 7 of x > Right, but also (considering the input stream as an array of bytes): > > var a = stream[i]; > a <<= 8; > a += stream[i+1]; No idea, outside of my knowledge. Rgds Denis McMahon |