diff options
| -rw-r--r-- | src/gallium/drivers/llvmpipe/lp_bld_arit.c | 54 |
1 files changed, 50 insertions, 4 deletions
diff --git a/src/gallium/drivers/llvmpipe/lp_bld_arit.c b/src/gallium/drivers/llvmpipe/lp_bld_arit.c index 83ca06acf8..93e797cb44 100644 --- a/src/gallium/drivers/llvmpipe/lp_bld_arit.c +++ b/src/gallium/drivers/llvmpipe/lp_bld_arit.c @@ -361,6 +361,8 @@ lp_build_mul(struct lp_build_context *bld, LLVMValueRef b) { const struct lp_type type = bld->type; + LLVMValueRef shift; + LLVMValueRef res; if(a == bld->zero) return bld->zero; @@ -394,10 +396,31 @@ lp_build_mul(struct lp_build_context *bld, assert(0); } - if(LLVMIsConstant(a) && LLVMIsConstant(b)) - return LLVMConstMul(a, b); + if(type.fixed) + shift = lp_build_int_const_scalar(type, type.width/2); + else + shift = NULL; - return LLVMBuildMul(bld->builder, a, b, ""); + if(LLVMIsConstant(a) && LLVMIsConstant(b)) { + res = LLVMConstMul(a, b); + if(shift) { + if(type.sign) + res = LLVMConstAShr(res, shift); + else + res = LLVMConstLShr(res, shift); + } + } + else { + res = LLVMBuildMul(bld->builder, a, b, ""); + if(shift) { + if(type.sign) + res = LLVMBuildAShr(bld->builder, res, shift, ""); + else + res = LLVMBuildLShr(bld->builder, res, shift, ""); + } + } + + return res; } @@ -432,13 +455,36 @@ lp_build_div(struct lp_build_context *bld, } +/** + * Linear interpolation. + * + * This also works for integer values with a few caveats. + * + * @sa http://www.stereopsis.com/doubleblend.html + */ LLVMValueRef lp_build_lerp(struct lp_build_context *bld, LLVMValueRef x, LLVMValueRef v0, LLVMValueRef v1) { - return lp_build_add(bld, v0, lp_build_mul(bld, x, lp_build_sub(bld, v1, v0))); + LLVMValueRef delta; + LLVMValueRef res; + + delta = lp_build_sub(bld, v1, v0); + + res = lp_build_mul(bld, x, delta); + + res = lp_build_add(bld, v0, res); + + if(bld->type.fixed) + /* XXX: This step is necessary for lerping 8bit colors stored on 16bits, + * but it will be wrong for other uses. Basically we need a more + * powerful lp_type, capable of further distinguishing the values + * interpretation from the value storage. */ + res = LLVMBuildAnd(bld->builder, res, lp_build_int_const_scalar(bld->type, (1 << bld->type.width/2) - 1), ""); + + return res; } |