diff options
| -rw-r--r-- | apps/plugins/jpeg.c | 11 |
1 files changed, 5 insertions, 6 deletions
diff --git a/apps/plugins/jpeg.c b/apps/plugins/jpeg.c index 5ecd394..9a32a8c 100644 --- a/apps/plugins/jpeg.c +++ b/apps/plugins/jpeg.c @@ -200,12 +200,11 @@ INLINE unsigned range_limit(int value) ); return value; #elif defined(CPU_ARM) - asm ( - "adds %[v], %[v], #128\n" /* value += 128 */ - "movmi %[v], #0 \n" /* clip to 0 if negative result */ - "cmp %[v], #255 \n" /* did we exceed 255? */ - "movgt %[v], #255 \n" /* yes, clip to limit */ - : + asm ( /* Note: Uses knowledge that only the low byte of the result is used */ + "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 */ [v]"+r"(value) ); return value; |