Intel i960 - Page 252

Language Implementation
7-63
7
• "dI" (new_mask) is the only input-spec . It is operand 1. The "dI"
constraint indicates that operand 1 must be in a word register, or be
a constant from 0 to 31. The compiler generates extra code as
necessary to make sure
new_mask matches one of the constraints
before the asm is generated.
Example 3: emul.c
The example refers to Example 7-3 below. The asm containing the
emul
instruction is shown in bold.
Example 7-3 emul.c
typedef struct
{
unsigned int lo32;
int hi32;
} int64;
typedef int int32;
static inline
int64 asm_emul(int32 in1, int32 in2)
{
int64 temp;
asm("emul %1,%2,%0" : "=t" (temp)
: "dI" (in1), "dI" (in2));
return temp;
}
int32 mul32_check_overflow(int32 a, int32 b)
{
int64 t;
t = asm_emul(a, b);
if ((t.lo32 & 0x80000000) != 0)
{
if (t.hi32 == -1) /*upper32 matches lower32 sign bit*/
continued ☛