Tema 020217

Pagina 1

Formal Languages and Compilers Proff. Breveglieri and Morzenti Written exam1: laboratory question 02/02/2017 SURNAME: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . NAME: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Student ID:. . . . . . . . . . . . . . . . Course: ◦ Laurea Specialistica ◦ V. O. ◦ Laurea Triennale ◦ Other: . . . Instructor: ◦ Prof. Breveglieri ◦ Prof Morzenti The laboratory question must be answered taking into account the implementation of the Acse compiler given with the exam text. Modify the specification of the lexical analyser ( flex input) and the syntactic analyser (bison input) and any other source file required to extend theLance language with the operator (bit). The operator can be written in front of a variable identifier . It transforms a vector v of integers into an integer, according to the following semantics: if v[i] is 0 then the i-th corresponding bit of ( bit)v is 0, otherwise if v[i] is non 0 then the i-th corresponding bit is 1. In any case, at most 32 elements of the vector are considered ( int variables are defined over 32 bits). Note that, if (bit) is applied in front of an identifier of a scalar, the returned value is the same as the one stored in the variable (namely, no translation is carried out). int v1[3]; int v2[1]; int v3[40]; int x = 10; //v1 encodes 110 v1[2] = 15; v1[1] = 79; v1[0] = 0; //v2 encodes 1 v2[0] = 1; //v3 encodes -2ˆ(31) v3[31]=37; write((bit)v1); //output 6 write((bit)v2); //output 1 write((bit)v3); //output -2ˆ(31) write((bit)x); //output 10 1Time 60’. Textbooks and notes can be used. Pencil writing is allowed. Write your name on any additional sheet. 1 1.…