ALU当然是处理器内核的一个重要单元,我们来看图说话:
再来一张放大图:
ALU的全称是Arithmetic Logic Unit!中文是不是应该叫算术逻辑单元?还是来英文吧。
Two 40-bit ALUs operating on 16-bit, 32-bit, and 40-bit input operands and output 16-bit, 32-bit, and 40-bit results.
Functions
-
Fixed-point addition and subtraction
-
Addition and subtraction of immediate values
-
Accumulator and subtraction of multiplier results
-
Logical AND, OR, NOT, XOR, bitwise_XOR, Negate
-
Functions: ABS, MAX, MIN, Round, division primitives
-
Supports conditional instructions
Four 8-bit video ALUs :Explained in more detail as part of Advanced Instructions section
ALU Operations :Conditional Code (CC) Bit in ASTAT
CC bit is used in several instructions
-
Action taken in the instruction depends on the value of CC
-
If cc jump here; //if cc = 1, jump to label “here”
-
If cc r3 = r0; // perform move if cc=1
CC bit value is based on a comparison of two registers, pointers or accumulators;CC bit can be moved to and from a data register or ASTAT bit;CC bit can be negated;
下一篇就准备简单说一下MAC,全称:MULTIPLY-ACCUMULATORS
用户402158 2014-7-25 11:08