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6 - Some Assembly Required
The ASM compare function operates the same as the C, but of course faster - qsort() is sped up by about 25%:
ASM_Code_Compare
; prototype:
;
; int ASM_Code_Compare(const void *ptrA,const void *ptrB);
;
; equivalent to:
;
; return *((unsigned long*)ptrA) - *((unsigned long*)ptrB);
;
; compare two longs pointed to by pointers in r0, r1
; we use r2 and r3 for workspace, and need no other
; registers, so no pushing
;
mov r1,t ; get long value pointed to by r1
mov32 (t),r2 ; and save in r2
mov r0,t ; get long value pointed to by r0
mov32 (t),r3 ; save into r3-but we really only need t's value
rptr r2
sub rp ; subtract the two
mov t,r0 ; place result in r0 for return
rts
The format may appear odd, since this is
assembly code in its natural state, not as
part of a C function. To code in this way,
the source was created as the file 'func.s',
and the makefile modified to compile it:SRCS_CPP = eg_12.cpp eg_12_form.cpp SRCS_C = SRCS_S = func.s
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