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use multiply-shift to scale reciprocals for rgb16 output, instead of

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multiply-divide

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@19788 a1c6a512-1295-4272-9138-f99709370657
This commit is contained in:
Andrew Mahone 2009-01-18 02:45:22 +00:00
parent 0229ec679b
commit 5ad02f701b
1 changed files with 8 additions and 5 deletions
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13
apps/plugins/pictureflow.c
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@ -397,6 +397,9 @@ static inline PFreal fcos(int iangle)
return fsin(iangle + (IANGLE_MAX >> 2)); return fsin(iangle + (IANGLE_MAX >> 2));
} }
#define RB_DIV ((31ULL << 32) / 255 + 1)
#define G_DIV ((63ULL << 32) / 255 + 1)
static void output_row_transposed(uint32_t row, void * row_in, static void output_row_transposed(uint32_t row, void * row_in,
struct scaler_context *ctx) struct scaler_context *ctx)
{ {
@ -408,11 +411,11 @@ static void output_row_transposed(uint32_t row, void * row_in,
*dest = ((*qp++) + ctx->round) * (uint64_t)ctx->divisor >> 32; *dest = ((*qp++) + ctx->round) * (uint64_t)ctx->divisor >> 32;
#else #else
struct uint32_rgb *qp = (struct uint32_rgb*)row_in; struct uint32_rgb *qp = (struct uint32_rgb*)row_in;
uint32_t rb_mul = ((uint64_t)ctx->divisor * 31 + 127) / 255, uint32_t rb_mul = ctx->divisor * (uint64_t)RB_DIV >> 32,
rb_rnd = ((uint64_t)ctx->round * 31 + 127) / 255, rb_rnd = ctx->round * (uint64_t)RB_DIV >> 32,
g_mul = ((uint64_t)ctx->divisor * 63 + 127) / 255, g_mul = ctx->divisor * (uint64_t)G_DIV >> 32,
g_rnd = ((uint64_t)ctx->round * 63 + 127) / 255; g_rnd = ctx->round * (uint64_t)G_DIV >> 32;
unsigned int r, g, b; int r, g, b;
for (; dest < end; dest += ctx->bm->height) for (; dest < end; dest += ctx->bm->height)
{ {
r = (qp->r + rb_rnd) * (uint64_t)rb_mul >> 32; r = (qp->r + rb_rnd) * (uint64_t)rb_mul >> 32;