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3  * Copyright 2009 VMware, Inc.
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27 
28 /**
29  * @file
30  * Position and shader input interpolation.
31  *
32  * Special attention is given to the interpolation of side by side quads.
33  * Multiplications are made only for the first quad. Interpolation of
34  * inputs for posterior quads are done exclusively with additions, and
35  * perspective divide if necessary.
36  *
37  * @author Jose Fonseca <jfonseca@vmware.com>
38  */
39 
40 #ifndef LP_BLD_INTERP_H
41 #define LP_BLD_INTERP_H
42 
43 
44 #include "gallivm/lp_bld.h"
45 #include "gallivm/lp_bld_type.h"
46 
47 #include "tgsi/tgsi_exec.h"
48 
49 /**
50  * Describes how to compute the interpolation coefficients (a0, dadx, dady)
51  * from the vertices passed into our triangle/line/point functions by the
52  * draw module.
53  *
54  * Vertices are treated as an array of float[4] values, indexed by
55  * src_index.
56  *
57  * LP_INTERP_COLOR is translated to either LP_INTERP_CONSTANT or
58  * PERSPECTIVE depending on flatshade state.
59  */
60 enum lp_interp {
61    LP_INTERP_CONSTANT,
62    LP_INTERP_COLOR,
63    LP_INTERP_LINEAR,
64    LP_INTERP_PERSPECTIVE,
65    LP_INTERP_POSITION,
66    LP_INTERP_FACING
67 };
68 
69 struct lp_shader_input {
70    uint interp:4;       /* enum lp_interp */
71    uint usage_mask:4;   /* bitmask of TGSI_WRITEMASK_x flags */
72    uint src_index:8;    /* where to find values in incoming vertices */
73    uint cyl_wrap:4;     /* TGSI_CYLINDRICAL_WRAP_x flags */
74    uint padding:12;
75 };
76 
77 
78 struct lp_build_interp_soa_context
79 {
80    /* TGSI_QUAD_SIZE x float */
81    struct lp_build_context coeff_bld;
82    struct lp_build_context setup_bld;
83 
84    unsigned num_attribs;
85    unsigned mask[1 + PIPE_MAX_SHADER_INPUTS]; /**< TGSI_WRITE_MASK_x */
86    enum lp_interp interp[1 + PIPE_MAX_SHADER_INPUTS];
87    boolean simple_interp;
88    boolean dynamic_offsets;
89 
90    LLVMValueRef x;
91    LLVMValueRef y;
92 
93    LLVMValueRef a[1 + PIPE_MAX_SHADER_INPUTS][TGSI_NUM_CHANNELS];
94    LLVMValueRef dadq[1 + PIPE_MAX_SHADER_INPUTS][TGSI_NUM_CHANNELS];
95    LLVMValueRef a0aos[1 + PIPE_MAX_SHADER_INPUTS];
96    LLVMValueRef dadxaos[1 + PIPE_MAX_SHADER_INPUTS];
97    LLVMValueRef dadyaos[1 + PIPE_MAX_SHADER_INPUTS];
98 
99    LLVMValueRef oow;
100 
101    LLVMValueRef attribs[1 + PIPE_MAX_SHADER_INPUTS][TGSI_NUM_CHANNELS];
102 
103    LLVMValueRef xoffset_store;
104    LLVMValueRef yoffset_store;
105 
106    /*
107     * Convenience pointers. Callers may access this one.
108     */
109    const LLVMValueRef *pos;
110    const LLVMValueRef (*inputs)[TGSI_NUM_CHANNELS];
111 };
112 
113 
114 void
115 lp_build_interp_soa_init(struct lp_build_interp_soa_context *bld,
116                          struct gallivm_state *gallivm,
117                          unsigned num_inputs,
118                          const struct lp_shader_input *inputs,
119                          LLVMBuilderRef builder,
120                          struct lp_type type,
121                          boolean dynamic_offsets,
122                          LLVMValueRef a0_ptr,
123                          LLVMValueRef dadx_ptr,
124                          LLVMValueRef dady_ptr,
125                          LLVMValueRef x,
126                          LLVMValueRef y);
127 
128 void
129 lp_build_interp_soa_update_inputs(struct lp_build_interp_soa_context *bld,
130                                   struct gallivm_state *gallivm,
131                                   int quad_start_index);
132 
133 void
134 lp_build_interp_soa_update_pos(struct lp_build_interp_soa_context *bld,
135                                struct gallivm_state *gallivm,
136                                int quad__start_index);
137 
138 void
139 lp_build_interp_soa_update_inputs_dyn(struct lp_build_interp_soa_context *bld,
140                                       struct gallivm_state *gallivm,
141                                       LLVMValueRef quad_start_index);
142 
143 void
144 lp_build_interp_soa_update_pos_dyn(struct lp_build_interp_soa_context *bld,
145                                    struct gallivm_state *gallivm,
146                                    LLVMValueRef quad_start_index);
147 
148 #endif /* LP_BLD_INTERP_H */
149