1. Thumb code has a number of different instruction codes for programme branches; three of these are given in Figure Q1 below. In what situations are each of these branch instructions used? What are the ranges of the branch destination for type (1) and type (2) branches?

2. By what mechanism does the Thumb branch and linkinstruction, type (3) above, achieve a range of branch destinations up to 4 MBytes relative to the programme counter?

15 12 11 8.7 1101 cond 8-bit offset (1) B 15 11 10 | 11100 11-bit offset (2) B 15 12 11 10 1111 H 1 1-bit offset (3) BL Figure Q1 15 12 11 8.7 1101 cond 8-bit offset (1) B 15 11 10 | 11100 11-bit offset (2) B 15 12 11 10 1111 H 1 1-bit offset (3) BL Figure Q1