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Enhanced the existing ARMExpandImm() and ThumbExpandImm() functions which expand 

an imm12 into imm32 for ARM or Thumb so that they now handle carry_in/carry_out.
Funnel ARMExpandImm()/ThumbExpandImm() to the enhanced ARMExpandImm_C()/ThumbExpandImm_C()
functions.

llvm-svn: 125508
This commit is contained in:
Johnny Chen 2011-02-14 19:08:41 +00:00
parent f0619868ae
commit e2b86a3a83
1 changed files with 66 additions and 35 deletions
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101
lldb/source/Plugins/Process/Utility/ARMUtils.h
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@ -32,47 +32,78 @@ static uint32_t ror(uint32_t val, uint32_t N, uint32_t shift)
return (val >> m) | (val << (N - m));
}
// (imm32, carry_out) = ARMExpandImm_C(imm12, carry_in)
static inline uint32_t ARMExpandImm_C(uint32_t val, uint32_t carry_in, uint32_t &carry_out)
{
uint32_t imm32; // the expanded result
uint32_t imm = bits(val, 7, 0); // immediate value
uint32_t amt = 2 * bits(val, 11, 8); // rotate amount
if (amt == 0)
{
imm32 = imm;
carry_out = carry_in;
}
else
{
imm32 = ror(imm, 32, amt);
carry_out = Bit32(imm32, 31);
}
return imm32;
}
static inline uint32_t ARMExpandImm(uint32_t val)
{
uint32_t imm = bits(val, 7, 0); // immediate value
uint32_t rot = 2 * bits(val, 11, 8); // rotate amount
return (imm >> rot) | (imm << (32 - rot));
// 'carry_in' argument to following function call does not affect the imm32 result.
uint32_t carry_in = 0;
uint32_t carry_out;
return ARMExpandImm_C(val, carry_in, carry_out);
}
// (imm32, carry_out) = ThumbExpandImm_C(imm12, carry_in)
static inline uint32_t ThumbExpandImm_C(uint32_t val, uint32_t carry_in, uint32_t &carry_out)
{
uint32_t imm32;
const uint32_t i = bit(val, 26);
const uint32_t imm3 = bits(val, 14, 12);
const uint32_t abcdefgh = bits(val, 7, 0);
const uint32_t imm12 = i << 11 | imm3 << 8 | abcdefgh;
if (bits(imm12, 11, 10) == 0)
{
switch (bits(imm12, 8, 9)) {
case 0:
imm32 = abcdefgh;
break;
case 1:
imm32 = abcdefgh << 16 | abcdefgh;
break;
case 2:
imm32 = abcdefgh << 24 | abcdefgh << 8;
break;
case 3:
imm32 = abcdefgh << 24 | abcdefgh << 16 | abcdefgh << 8 | abcdefgh;
break;
}
carry_out = carry_in;
}
else
{
const uint32_t unrotated_value = 0x80 | bits(imm12, 6, 0);
imm32 = ror(unrotated_value, 32, bits(imm12, 11, 7));
carry_out = Bit32(imm32, 31);
}
return imm32;
}
static inline uint32_t ThumbExpandImm(uint32_t val)
{
uint32_t imm32 = 0;
const uint32_t i = bit(val, 26);
const uint32_t imm3 = bits(val, 14, 12);
const uint32_t abcdefgh = bits(val, 7, 0);
const uint32_t imm12 = i << 11 | imm3 << 8 | abcdefgh;
if (bits(imm12, 10, 11) == 0)
{
switch (bits(imm12, 8, 9)) {
case 0:
imm32 = abcdefgh;
break;
case 1:
imm32 = abcdefgh << 16 | abcdefgh;
break;
case 2:
imm32 = abcdefgh << 24 | abcdefgh << 8;
break;
case 3:
imm32 = abcdefgh << 24 | abcdefgh << 16 | abcdefgh << 8 | abcdefgh;
break;
}
}
else
{
const uint32_t unrotated_value = 0x80 | bits(imm12, 0, 6);
imm32 = ror(unrotated_value, 32, bits(imm12, 7, 11));
}
return imm32;
// 'carry_in' argument to following function call does not affect the imm32 result.
uint32_t carry_in = 0;
uint32_t carry_out;
return ThumbExpandImm_C(val, carry_in, carry_out);
}
// imm32 = ZeroExtend(i:imm3:imm8, 32)