Zack Buhman
9610c428bd
This draws a nice macaw texture in a square-shaped triangle strip. The square is then rotated around the y-axis. I dealt with myriad bugs while experimenting with this, all of them entirely my fault: - macaw texture colors were incorrect because GIMP was exporting raw RGB data in gamma-corrected sRGB space, whereas the Dreamcast is in linear color space. - macaw texture colors were incorrect because I truncated color values to the least significant rather than most significant bits. - macaw rotation around the Y axis caused the macaw texture to distort, stretch and recurse in interesting and unexpected ways. This was caused by sending Z values in the wrong coordinate space (Z) contrast to what is expected by the Dreamcast (1/z). Reordering z-coordinate operations so that the reciprocal is computed last resolved this. - macaw rotation around the Y axis caused the macaw texture to warp unexpectedly, but only on real hardware. This was caused by unnecessarily negating Z coordinate values. Behavior for each of the Z-coordinate issues differed between Flycast and real Dreamcast hardware. I also did several tests related to SH4 cache behavior, particularly related to the "copy-back" mode. I verified copy-back behavior on a real dreamcast, and experimented with the operand cache write-back instruction, "ocbwb". In particular, when the `scene` buffer is access from cacheable memory, e.g: the P1 area, and CCR__CB is enabled, DMA from physical memory to the TA FIFO polygon converter will fail because the scene data has not yet been written to physical memory yet. `ocbwb` can be used to "write back" scene from the SH4 operand cache to physical memory--only the latter is visible from the CH2-DMA perspective.
148 lines
4.5 KiB
C++
148 lines
4.5 KiB
C++
#include <cstdint>
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namespace isp_tsp_instruction_word {
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namespace depth_compare_mode {
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constexpr uint32_t never = 0 << 29;
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constexpr uint32_t less = 1 << 29;
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constexpr uint32_t equal = 2 << 29;
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constexpr uint32_t less_or_equal = 3 << 29;
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constexpr uint32_t greater = 4 << 29;
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constexpr uint32_t not_equal = 5 << 29;
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constexpr uint32_t greater_or_equal = 6 << 29;
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constexpr uint32_t always = 7 << 29;
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}
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namespace culling_mode {
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constexpr uint32_t no_culling = 0 << 27;
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constexpr uint32_t cull_if_small = 1 << 27; // compared to FPU_CULL_VAL
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constexpr uint32_t cull_if_negative = 2 << 27;
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constexpr uint32_t cull_if_positive = 3 << 27;
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}
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constexpr uint32_t z_write_disable = 1 << 26;
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constexpr uint32_t texture = 1 << 25;
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constexpr uint32_t offset = 1 << 24;
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constexpr uint32_t gouraud_shading = 1 << 23;
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constexpr uint32_t _16bit_uv = 1 << 22;
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constexpr uint32_t cache_bypass = 1 << 21;
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constexpr uint32_t dcalc_ctrl = 1 << 20;
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}
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namespace tsp_instruction_word {
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namespace src_alpha_instr {
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constexpr uint32_t zero = 0 << 29;
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constexpr uint32_t one = 1 << 29;
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constexpr uint32_t other_color = 2 << 29;
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constexpr uint32_t inverse_other_color = 3 << 29;
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constexpr uint32_t src_alpha = 4 << 29;
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constexpr uint32_t inverse_src_alpha = 5 << 29;
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constexpr uint32_t dst_alpha = 6 << 29;
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constexpr uint32_t inverse_dst_alpha = 7 << 29;
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}
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namespace dst_alpha_instr {
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constexpr uint32_t zero = 0 << 26;
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constexpr uint32_t one = 1 << 26;
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constexpr uint32_t other_color = 2 << 26;
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constexpr uint32_t inverse_other_color = 3 << 26;
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constexpr uint32_t src_alpha = 4 << 26;
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constexpr uint32_t inverse_src_alpha = 5 << 26;
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constexpr uint32_t dst_alpha = 6 << 26;
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constexpr uint32_t inverse_dst_alpha = 7 << 26;
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}
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constexpr uint32_t src_select = 1 << 25;
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constexpr uint32_t dst_select = 1 << 24;
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namespace fog_control {
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constexpr uint32_t look_up_table = 0b00 << 22;
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constexpr uint32_t per_vertex = 0b01 << 22;
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constexpr uint32_t no_fog = 0b10 << 22;
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constexpr uint32_t look_up_table_mode_2 = 0b11 << 22;
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}
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constexpr uint32_t color_clamp = 1 << 21;
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constexpr uint32_t use_alpha = 1 << 20;
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constexpr uint32_t ignore_tex_alpha = 1 << 19;
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namespace flip_uv {
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constexpr uint32_t none = 0 << 17;
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constexpr uint32_t v = 1 << 17;
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constexpr uint32_t u = 2 << 17;
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constexpr uint32_t uv = 3 << 17;
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}
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namespace clamp_uv {
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constexpr uint32_t none = 0 << 15;
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constexpr uint32_t v = 1 << 15;
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constexpr uint32_t u = 2 << 15;
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constexpr uint32_t uv = 3 << 15;
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}
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namespace filter_mode {
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constexpr uint32_t point_sampled = 0b00 << 13;
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constexpr uint32_t bilinear_filter = 0b01 << 13;
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constexpr uint32_t trilinear_pass_a = 0b10 << 13;
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constexpr uint32_t trilinear_pass_b = 0b11 << 13;
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}
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constexpr uint32_t super_sample_texture = 1 << 12;
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constexpr uint32_t mip_map_d_adjust(uint32_t fp)
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{
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return (fp & 0b1111) << 8;
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}
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namespace texture_shading_instruction {
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constexpr uint32_t decal = 0 << 6;
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constexpr uint32_t modulate = 1 << 6;
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constexpr uint32_t decal_alpha = 2 << 6;
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constexpr uint32_t modulate_alpha = 3 << 6;
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}
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namespace texture_u_size {
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constexpr uint32_t _8 = 0 << 3;
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constexpr uint32_t _16 = 1 << 3;
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constexpr uint32_t _32 = 2 << 3;
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constexpr uint32_t _64 = 3 << 3;
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constexpr uint32_t _128 = 4 << 3;
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constexpr uint32_t _256 = 5 << 3;
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constexpr uint32_t _512 = 6 << 3;
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constexpr uint32_t _1024 = 7 << 3;
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}
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namespace texture_v_size {
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constexpr uint32_t _8 = 0 << 0;
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constexpr uint32_t _16 = 1 << 0;
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constexpr uint32_t _32 = 2 << 0;
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constexpr uint32_t _64 = 3 << 0;
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constexpr uint32_t _128 = 4 << 0;
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constexpr uint32_t _256 = 5 << 0;
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constexpr uint32_t _512 = 6 << 0;
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constexpr uint32_t _1024 = 7 << 0;
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}
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}
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namespace texture_control_word {
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constexpr uint32_t mip_mapped = 1 << 31;
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constexpr uint32_t vq_compressed = 1 << 30;
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namespace pixel_format {
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constexpr uint32_t _1555 = 0 << 27;
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constexpr uint32_t _565 = 1 << 27;
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constexpr uint32_t _4444 = 2 << 27;
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constexpr uint32_t yuv422 = 3 << 27;
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constexpr uint32_t bump_map = 4 << 27;
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constexpr uint32_t _4bpp_palette = 5 << 27;
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constexpr uint32_t _8bpp_palette = 6 << 27;
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}
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constexpr uint32_t scan_order = 1 << 26;
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constexpr uint32_t stride_select = 1 << 25;
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// in 8-byte units
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constexpr uint32_t texture_address(uint32_t a) {
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return a & 0x1fffff;
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}
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}
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