【Mac - i386 Registers】
Registers
Many instructions accept registers as operands. The OS X assembler for Intel i386 processors always uses names beginning with a percent sign (‘%’) for registers, so naming conflicts with identifiers aren’t possible; further, all register names are in lowercase letters.
There're 4 kinds of register in i386:
1、general registers
2、segment registers
3、floating point registers
4、other registers
General Registers
Each of the 32-bit general registers of the i386 architecture are accessible by different names, which specify parts of that register to be used. For example, the AX register can be accessed as a single byte (%ah or %al), a 16-bit value (%ax), or a 32-bit value (%eax). The figure below shows the names of these registers and their relation to the full 32-bit storage for each register:
