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Slight snake opt, discovered PA tri over yield negative

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Sauraen
2025-09-28 17:35:08 -07:00
parent dfbba19f9f
commit 9866c95c35
1 changed files with 7 additions and 7 deletions
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14
f3dex3.s
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@@ -1316,7 +1316,6 @@ align_with_warning 8, "One instruction of padding before tri snake"
tri_snake_ret_from_input_buffer:
lpv $v30[2], (inputBufferEndSgn)(inputBufferPos) // c (pos+0) to elem 2
lbu $3, (inputBufferEnd)(inputBufferPos) // Load c; clear real index b sign bit -> don't exit
vand $v6, $v30, vTRC_7E00 // Mask out dir flag and end flag
j tri_snake_loop_from_input_buffer // inputBufferPos pointing to first byte loaded
G_TRISNAKE_handler:
li $ra, tri_snake_loop // For both init and above (clobbered by DMA).
@@ -1328,21 +1327,22 @@ tri_snake_loop:
// $v30 elem 2 has new index c, which will become new origV1Addr.
// origV1Addr has last one, which gets stored to the V2 or V3 spot.
lh $3, (inputBufferEnd)(inputBufferPos) // Load indices b and c
vand $v6, $v30, vTRC_7E00 // Mask out dir flag and end flag
addi inputBufferPos, inputBufferPos, 1 // Increment indices being read
tri_snake_loop_from_input_buffer:
vand $v6, $v30, vTRC_7E00 // Mask out dir flag and end flag
vmudn $v29, vOne, vTRC_VB // Address of vertex buffer
beqz inputBufferPos, tri_snake_over_input_buffer // == 0 at end of input buffer
andi $11, $3, 1 // Get direction flag from index c
sll $11, $11, 1 // Halfword address
snake_c_to_v30
vmadl $v6, $v6, vTRC_VS // Plus vtx indices times length
bltz $3, tri_snake_end // Upper bit of real index b set = done
sll $11, $11, 1 // Halfword address
sh origV1Addr, (rdpHalf1Val)($11) // Store old v1 as 2 if dir clear or 3 if set
llv $v7[4], (rdpHalf1Val - altBase)(altBaseReg) // Load addresses 2, 3 to elem 2, 3
bltz $3, tri_snake_end // Upper bit of real index b set = done
llv $v7[4], (rdpHalf1Val - altBase)(altBaseReg) // Load addresses 2, 3 to elem 2, 3
mfc2 origV1Addr, $v6[4] // In elem 2 (not elem 1 like 1tri)
lh $2, (rdpHalf1Val + 0)($zero)
j tri_from_snake // Repeat next instr so we can skip lbu origV1Addr
snake_c_to_v30
lh $2, (rdpHalf1Val + 0)($zero)
// H = highest on screen = lowest Y value; then M = mid, L = low
tHAtF equ $v5