Red Hat ENTERPRISE LINUX 4 Manual page 201

Chapter 6. Extensions to the C Language Family
P
Positive 16-bit constant
G
Floating point zero
Q
Memory reference that can be loaded with more than one instruction (
statements)
asm
R
Memory reference that can be loaded with one instruction (
ments)
S
Memory reference in external OSF/rose PIC format (
Motorola 680x0--
m68k.h
a
Address register
d
Data register
f
68881 floating-point register, if available
I
Integer in the range 1 to 8
J
16-bit signed number
K
Signed number whose magnitude is greater than 0x80
L
Integer in the range -8 to -1
M
Signed number whose magnitude is greater than 0x100
G
Floating point constant that is not a 68881 constant
m
is preferable for
m
is preferable for
m asm
193
is preferable for
state-
asm
statements)