HELP! - PicBasic Pro - What does this mean?

[SwingeyP]

a = a < < 1

I came across this in some code. What is it trying to do?

Thank you

 

[3v0]

shift left
The << operator shifts the binary representation to the left, dropping the most significant bits and appending it with zero bits. The result is equivalent to multiplying the integer by a power of two.

if you start with
x = 0b00000001
and do
x = x << 1
x will be 0b00000010

you can also shift by more then one bit
x = x << 3
will shift 3 bit positions

 

[SwingeyP]

Ahhh - I see. Many thanks for that.

I am trying to convert some code from Pic Basic Pro to OShon and i'm having some trouble with bits and bytes. Can you help with this please?

Original Pic Basic Pro Code

; = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
; = = fts - 8 replacement(ctcss encoder For yaesu = =
; = = by manfred mornhinweg, may 2010 = =
; = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =


'============================== Pin definitions ==============
toneout var PORTA.1
s1 var PORTB.0
s2 var PORTB.1
s3 var PORTB.2
s4 var PORTB.3
s5 var PORTA.2
s6 var PORTA.3
e var PORTA.4
'TX is fixed at MCLR

'============================ variables ======================
tnum var Byte ;tone number from radio
frec var Word ;tone frequency x 5

Define osc 20 ;trick compiler into thinking the crystal is 20mhz, To get better freq resolution.

CMCON = 7 ;Disable comparators, Enable digital functions On PORTA



'=============Main============
toneoff: If e = 0 Then Goto toneoff ;tones are disabled, just idle

tnum = s6 ;Read tone number, independent of pins
tnum = tnum < < 1
tnum = tnum + s5
tnum = tnum < < 1
tnum = tnum + s4
tnum = tnum < < 1
tnum = tnum + s3
tnum = tnum < < 1
tnum = tnum + s2
tnum = tnum < < 1
tnum = tnum + s1
tnum = tnum - 20 ;make first tone number zero

lookup2 tnum, [487, 457, 442, 427, 412, 398, 385, 372, 359, 335, 1251, 1209, 1168, 1128, 1090, 1053, 1017, 964, 931, 899, 869, 839, 811, 783, 757, 731, 706, 682, 659, 636, 615, 594, 574, 554, 536, 517, 500, 474, 442, 412, 385, 359, 335], frec

toneloop: FreqOut toneout, 0, frec
Goto toneloop



OSHON CODE - I have been messing with bits and bytes as it doesn't compile ....

Dim tnum As Byte
Dim freq As Word
Dim toneout As Bit

Dim s1 As Bit
Dim s2 As Bit
Dim s3 As Bit
Dim s4 As Bit
Dim s5 As Bit
Dim s6 As Byte

Dim e As Bit


toneout = PORTA.1
s1 = PORTB.0
s2 = PORTB.1
s3 = PORTB.2
s4 = PORTB.3
s5 = PORTA.2
s6 = PORTA.3
e = PORTA.4


'=============Main============
toneoff: If e = 0 Then Goto toneoff 'tones are disabled, just idle

tnum = s6 'Read tone number, independent of pins
tnum = ShiftLeft(tnum, 1)
tnum = tnum + s5
tnum = ShiftLeft(tnum, 1)
tnum = tnum + s4
tnum = ShiftLeft(tnum, 1)
tnum = tnum + s3
tnum = ShiftLeft(tnum, 1)
tnum = tnum + s2
tnum = ShiftLeft(tnum, 1)
tnum = tnum + s1
tnum = tnum - 20 'make first tone number zero

freq = LookUp(487, 457, 442, 427, 412, 398, 385, 372, 359, 335,
1251, 1209, 1168, 1128, 1090, 1053, 1017, 964, 931, 899,
869, 839, 811, 783, 757, 731, 706, 682, 659, 636,
615, 594, 574, 554, 536, 517, 500, 474, 442, 412,
385, 359, 335), tnum

toneloop: FreqOut toneout, freq, 0
Goto toneloop



Thanks for your help

 

[ronsimpson]

You can down load the PicBasicPro manual or use the online version. Do not get confused with PicBasic. (no Pro)