125 lines
2.6 KiB
ArmAsm
125 lines
2.6 KiB
ArmAsm
.global _azrp_image_shader_rgb16_normal
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#include "image_macros.S"
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/* RGB16 Opaque rendering, Azur version: by straightforward copy.
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This function of the image renderer is designed for Azur's streaming model
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only. Unlike its RAM-model counterpart which is bottlenecked by its writing
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speed, this function is entirely limited by the CPU's ability to output the
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data in the required format.
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In the simple case where there is no color effect and no HFLIP, the task of
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rendering a 16-bit opaque image boils down to a 2-dimensional memcpy. This
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task can be optimized by moving longwords if the source and destination are
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co-4-aligned, with four variations depending on the width and initial
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position, identified by the following parameters:
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* w1 / w2 denotes the parity of the command width;
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* o2 / o4 denotes the alignment of the output.
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It is easy to see that when input and output are not co-aligned, any attempt
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to combine two word reads into a single long write requires at least 3
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cycles per 2 pixels and needs parallelism over several pixels to not get
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immediately shut down by the LS-to-EX delay. Here we decide to naively copy
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by words, which achieves 4 cycles per 2 pixels, mainly because large RGB16
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images are very quickly bottlenecked in reading by their own size anyway.
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The HFLIP version also needs to rearrange pixels, and is thus performed with
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word-based copies in all situations, which is a straightforward process. */
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_azrp_image_shader_rgb16_normal:
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/* Not a single cycle */
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tst #1, r0
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bf _BACKWARD_WORD_COPY
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mov #8, r0 /* Use the naive method for width ≤ 8 */
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cmp/ge r2, r0
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bt.s _FORWARD_WORD_COPY
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nop
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mov r5, r0 /* Check if r3 and r5 are co-aligned */
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xor r3, r0
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/* Not a single cycle */
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tst #2, r0
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bt _FORWARD_LONG_COPY
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_FORWARD_WORD_COPY:
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START
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2: movs.w @r3+, x0
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3: movs.w x0, @r5+
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END
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EPILOGUE
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_FORWARD_LONG_COPY:
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shlr r2 /* Test width parity */
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mov #2, r0
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bt .w1
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nop
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.w2: tst r0, r3 /* Test alignment of input */
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bf .w2d2
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.w2d4: START
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2: movs.l @r3+, x0
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3: movs.l x0, @r5+
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END
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EPILOGUE
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.w2d2: add #-1, r2
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nop
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START
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movs.w @r3+, x0
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movs.w x0, @r5+
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2: movs.l @r3+, x0
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3: movs.l x0, @r5+
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movs.w @r3+, x0
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movs.w x0, @r5+
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END
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EPILOGUE
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.w1: tst r0, r3 /* Test alignment of input */
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bf .w1d2
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.w1d4: START
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2: movs.l @r3+, x0
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3: movs.l x0, @r5+
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movs.w @r3+, x0
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movs.w x0, @r5+
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END
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EPILOGUE
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.w1d2: START
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movs.w @r3+, x0
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movs.w x0, @r5+
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2: movs.l @r3+, x0
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3: movs.l x0, @r5+
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END
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EPILOGUE
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_BACKWARD_WORD_COPY:
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mov r2, r0
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shll r0
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add r0, r5
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nop
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shll r0
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nop
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add r0, r6
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nop
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START
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2: movs.w @r3+, x0
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3: movs.w x0, @-r5
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END
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EPILOGUE
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