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Peephole optimizations #774

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2849210
srldrvce peephole optimizations
ZERICO2005 Mar 16, 2026
0b377f9
optimize validInterval branch
ZERICO2005 Mar 12, 2026
420f2e8
optimize str(r)str
ZERICO2005 Apr 5, 2026
bb271da
optimize some float routines
ZERICO2005 Mar 13, 2026
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16 changes: 8 additions & 8 deletions src/libc/ceilf.src
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Original file line number Diff line number Diff line change
Expand Up @@ -15,28 +15,28 @@

_ceil:
_ceilf:
call __frameset0
ld bc, (ix+6)
ld a, (ix+9)
ld hl, 6
add hl, sp
ld a, (hl)
dec hl
dec hl
dec hl
ld bc, (hl)
call __fneg
ld l, a
ld h, 0
push hl
push bc
call _floor
pop bc
pop bc
push hl
ex (sp), hl
pop bc
ld a, e
call __fneg
ld e, a
push bc
pop hl
pop ix
ret

.extern __frameset0
.extern __fneg
.extern _floor

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12 changes: 7 additions & 5 deletions src/libc/cimagf.src
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Expand Up @@ -10,9 +10,11 @@
; float cimagf(float _Complex)
_cimagf:
_cimag:
ld iy, 0
add iy, sp
ld sp, iy
ld hl, (iy + 7)
ld e, (iy + 10)
ld hl, 10
add hl, sp
ld e, (hl)
dec hl
dec hl
dec hl
ld hl, (hl)
ret
1 change: 0 additions & 1 deletion src/libc/cimagl.src
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Expand Up @@ -9,7 +9,6 @@
_cimagl:
ld iy, 0
add iy, sp
ld sp, iy
ld hl, (iy + 11)
ld de, (iy + 14)
ld bc, (iy + 17)
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7 changes: 3 additions & 4 deletions src/libc/strrstr.src
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Expand Up @@ -17,17 +17,16 @@ _strrstr:
ld bc, 0
cpir
sbc hl, hl
dec hl
sbc hl, bc ; carry will be cleared
scf
sbc hl, bc ; carry will be set
ex (sp), hl ; strlen(needle)
push hl ; needle

ex de, hl
push hl
ld bc, 0
ld bc, -1
cpir
sbc hl, hl
dec hl
sbc hl, bc
ex (sp), hl ; strlen(haystack)
push hl ; haystack
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7 changes: 3 additions & 4 deletions src/libc/strstr.src
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Expand Up @@ -24,17 +24,16 @@ _strstr:
ld bc, 0
cpir
sbc hl, hl
dec hl
sbc hl, bc ; carry will be cleared
scf
sbc hl, bc ; carry will be set
ex (sp), hl ; strlen(needle)
push hl ; needle

ex de, hl
push hl
ld bc, 0
ld bc, -1
cpir
sbc hl, hl
dec hl
sbc hl, bc
ex (sp), hl ; strlen(haystack)
push hl ; haystack
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26 changes: 8 additions & 18 deletions src/srldrvce/srldrvce.asm
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Expand Up @@ -523,8 +523,7 @@ srl_GetCDCStandardDescriptors:
jq nz,.noserial

ld a,3
ld hl,.device+deviceDescriptor.iSerialNumber
ld (hl),a
ld (.device+deviceDescriptor.iSerialNumber),a

ld de,.stringserialnum + 2
ld hl,ti.OP4
Expand All @@ -550,9 +549,7 @@ srl_GetCDCStandardDescriptors:
jq c,.store
add a,'A'-'9'-1
.store:
ex de,hl
ld (hl),a
ex de,hl
ld (de),a
inc de
inc de
ret
Expand Down Expand Up @@ -615,15 +612,12 @@ srl_UsbEventCallback:
push de
push de
call usb_FindDevice
pop de
pop de
pop de
ld sp, ix
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@runer112 runer112 Apr 5, 2026

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This wouldn't exactly a peephole optimization, but you could entirely remove this.

Suggested change
ld sp, ix

ld de, 0
push de
push hl
call usb_GetDeviceEndpoint
pop de
pop de
ld sp, ix
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This wouldn't exactly a peephole optimization, but you could entirely remove this.

Suggested change
ld sp, ix

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@ZERICO2005 ZERICO2005 Apr 5, 2026

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I realized we can also call .line_coding here to save another byte

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@ZERICO2005 ZERICO2005 Apr 5, 2026 •
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Although to be fair. If we need to save bytes we would just rewrite that whole function in assembly lol

ld de, 0
push de
push de
Expand All @@ -634,11 +628,7 @@ srl_UsbEventCallback:
push hl
call usb_ScheduleControlTransfer
ld bc, 1
pop hl
pop hl
pop hl
pop hl
pop hl
ld sp, ix
.BB0_5:
push bc
pop hl
Expand Down Expand Up @@ -668,7 +658,7 @@ get_device_type:
call next_descriptor
inc hl
inc hl
ld de,0
inc.s de ; clear UDE
ld e,(hl) ; total descriptor length
inc hl
ld d,(hl)
Expand Down Expand Up @@ -828,7 +818,7 @@ set_rate_cdc:
ld (.linecoding),hl
ld bc,0
push bc ; transferred
ld bc,50
ld c,50 ; ld bc, 50
push bc ; num retries
ld bc,.linecoding
push bc ; data
Expand Down Expand Up @@ -984,8 +974,8 @@ ring_buf_push:
sbc hl,hl ; check if bc is 0
adc hl,bc
ret z
ld hl,(xring_buf_ctrl.data_end)
ex de,hl ; hl = data
ld de,(xring_buf_ctrl.data_end)
push bc
ldir ; de = data_end + len
ld (xring_buf_ctrl.data_end),de
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4 changes: 2 additions & 2 deletions src/usbdrvce/usbdrvce.asm
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Expand Up @@ -2952,8 +2952,8 @@ assert endpointDescriptor.wMaxPacketSize+2 = endpointDescriptor.bInterval
inc hl
ld b,(hl)
inc b
djnz .validInterval
jq .invalidParam
dec b
jq z, .invalidParam
.validInterval:
ex de,hl
inc.s hl
Expand Down
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