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Move +128 offset out of range_limit, and add it to the DC coefficient in each idct*h routine, for a small binsize improvement on idct4h, idct8h, and idct16h, and a negligible speed increase.

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git-svn-id: svn://svn.rockbox.org/rockbox/trunk@21255 a1c6a512-1295-4272-9138-f99709370657
This commit is contained in:
Andrew Mahone 2009-06-11 23:48:37 +00:00
parent 235305e6ac
commit 57ccbdd198
1 changed files with 10 additions and 12 deletions
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22
apps/recorder/jpeg_load.c
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@ -123,8 +123,6 @@ INLINE unsigned range_limit(int value)
#if CONFIG_CPU == SH7034
unsigned tmp;
asm ( /* Note: Uses knowledge that only low byte of result is used */
"mov #-128,%[t] \n"
"sub %[t],%[v] \n" /* value -= -128; equals value += 128; */
"extu.b %[v],%[t] \n"
"cmp/eq %[v],%[t] \n" /* low byte == whole number ? */
"bt 1f \n" /* yes: no overflow */
@ -139,7 +137,6 @@ INLINE unsigned range_limit(int value)
#elif defined(CPU_COLDFIRE)
/* Note: Uses knowledge that only the low byte of the result is used */
asm (
"add.l #128,%[v] \n" /* value += 128; */
"cmp.l #255,%[v] \n" /* overflow? */
"bls.b 1f \n" /* no: return value */
/* yes: set low byte to appropriate boundary */
@ -152,7 +149,6 @@ INLINE unsigned range_limit(int value)
#elif defined(CPU_ARM)
/* Note: Uses knowledge that only the low byte of the result is used */
asm (
"add %[v], %[v], #128 \n" /* value += 128 */
"cmp %[v], #255 \n" /* out of range 0..255? */
"mvnhi %[v], %[v], asr #31 \n" /* yes: set all bits to ~(sign_bit) */
: /* outputs */
@ -160,8 +156,6 @@ INLINE unsigned range_limit(int value)
);
return value;
#else
value += 128;
if ((unsigned)value <= 255)
return value;
@ -265,7 +259,7 @@ static void idct1h(int16_t *ws, unsigned char *out, int rows, int rowstep)
int row;
for (row = 0; row < rows; row++)
{
*out = range_limit((int) DESCALE(*ws, 3 + PASS1_BITS));
*out = range_limit(128 + (int) DESCALE(*ws, 3 + PASS1_BITS));
out += rowstep;
ws += 8;
}
@ -291,7 +285,8 @@ static void idct2h(int16_t *ws, unsigned char *out, int rows, int rowstep)
int row;
for (row = 0; row < rows; row++)
{
int tmp1 = ws[0] + (ONE << (PASS1_BITS + 2));
int tmp1 = ws[0] + (ONE << (PASS1_BITS + 2))
+ (128 << (PASS1_BITS + 3));
int tmp2 = ws[1];
out[JPEG_PIX_SZ*0] = range_limit((int) RIGHT_SHIFT(tmp1 + tmp2,
PASS1_BITS + 3));
@ -350,7 +345,8 @@ static void idct4h(int16_t *ws, unsigned char *out, int rows, int rowstep)
{
/* Even part */
tmp0 = (int) ws[0] + (ONE << (PASS1_BITS + 2));
tmp0 = (int) ws[0] + (ONE << (PASS1_BITS + 2)
+ (128 << (PASS1_BITS + 3));
tmp2 = (int) ws[2];
tmp10 = (tmp0 + tmp2) << CONST_BITS;
@ -495,7 +491,7 @@ static void idct8h(int16_t *ws, unsigned char *out, int rows, int rowstep)
| ws[4] | ws[5] | ws[6] | ws[7]) == 0)
{
/* AC terms all zero */
unsigned char dcval = range_limit((int) DESCALE((long) ws[0],
unsigned char dcval = range_limit(128 + (int) DESCALE((long) ws[0],
PASS1_BITS+3));
out[JPEG_PIX_SZ*0] = dcval;
@ -520,7 +516,8 @@ static void idct8h(int16_t *ws, unsigned char *out, int rows, int rowstep)
tmp2 = z1 + MULTIPLY16(z3, - FIX_1_847759065);
tmp3 = z1 + MULTIPLY16(z2, FIX_0_765366865);
z4 = (long) ws[0] + (ONE << (PASS1_BITS + 2));
z4 = (long) ws[0] + (ONE << (PASS1_BITS + 2))
+ (128 << (PASS1_BITS + 3));
z4 <<= CONST_BITS;
z5 = (long) ws[4] << CONST_BITS;
tmp0 = z4 + z5;
@ -703,7 +700,8 @@ static void idct16h(int16_t *ws, unsigned char *out, int rows, int rowstep)
/* Even part */
/* Add fudge factor here for final descale. */
tmp0 = (long) ws[0] + (ONE << (PASS1_BITS+2));
tmp0 = (long) ws[0] + (ONE << (PASS1_BITS+2))
+ (128 << (PASS1_BITS + 3));
tmp0 <<= CONST_BITS;
z1 = (long) ws[4];