Cirrus Logic CS485 Instrukcja Użytkownika Pobierz pdf (Strona 26)

CS485G Spring 2015 26

25 x86 64 registers

1. Eight upgraded 64-bit registers, now with names starting with r in-

stead of e, such as %rax.

2. Eight new 64-bit registers, called %r8 . . . %r15.

3. To use only the lower bits of a register, append a sufﬁx to the register

name.

sufﬁx bits

b 8

w 16

d 32

4. Conventions

(a) The ﬁrst 6 parameters are passed, in reverse order, in %rdi,

%rsi, %rdx, %rcx, %r8, and %r9.

(b) The remaining parameters are pushed on the stack in call order.

%r14, and %r15.

(d) Other registers are volatile (caller-save).

26 Data types

1. Integer

(a) Can be stored in general registers or in memory.

(b) Signed and unsigned work the same except for shift operations.

Intel C assembler bytes

byte char b 1

word short w 2

double word int l 4

quad word long int q 8 (x86 64)

2. Floating point

(a) Can be stored in ﬂoating-point registers or in memory.

Intel C assembler bytes

single float s 4

double double l 8 (x86 64)

extended long double t 10/12/16 (x86 64)

1 2 ... 21 22 23 24 25 26 27 28 29 30 31 ... 66 67

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Cirrus Logic CS485 Instrukcja Użytkownika Strona 26