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//===-- ARMCommon.cpp - Define support functions for ARM --------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file was developed by the "Instituto Nokia de Tecnologia" and
// is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
//
//
//===----------------------------------------------------------------------===//
#include "ARMCommon.h"
static inline unsigned rotateL(unsigned x, unsigned n){
return ((x << n) | (x >> (32 - n)));
}
static inline unsigned rotateR(unsigned x, unsigned n){
return ((x >> n) | (x << (32 - n)));
}
// finds the end position of largest sequence of zeros in binary representation
// of 'immediate'.
static int findLargestZeroSequence(unsigned immediate){
int max_zero_pos = 0;
int max_zero_length = 0;
int zero_pos;
int zero_length;
int pos = 0;
int end_pos;
while ((immediate & 0x3) == 0) {
immediate = rotateR(immediate, 2);
pos+=2;
}
end_pos = pos+32;
while (pos<end_pos){
while (((immediate & 0x3) != 0)&&(pos<end_pos)) {
immediate = rotateR(immediate, 2);
pos+=2;
}
zero_pos = pos;
while (((immediate & 0x3) == 0)&&(pos<end_pos)) {
immediate = rotateR(immediate, 2);
pos+=2;
}
zero_length = pos - zero_pos;
if (zero_length > max_zero_length){
max_zero_length = zero_length;
max_zero_pos = zero_pos % 32;
}
}
return (max_zero_pos + max_zero_length) % 32;
}
std::vector<unsigned> splitImmediate(unsigned immediate){
std::vector<unsigned> immediatePieces;
if (immediate == 0){
immediatePieces.push_back(0);
} else {
int start_pos = findLargestZeroSequence(immediate);
unsigned immediate_tmp = rotateR(immediate, start_pos);
int pos = 0;
while (pos < 32){
while(((immediate_tmp&0x3) == 0)&&(pos<32)){
immediate_tmp = rotateR(immediate_tmp,2);
pos+=2;
}
if (pos < 32){
immediatePieces.push_back(rotateL(immediate_tmp&0xFF,
(start_pos + pos) % 32 ));
immediate_tmp = rotateR(immediate_tmp,8);
pos+=8;
}
}
}
return immediatePieces;
}
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