From ce673578fdcdf197648bbba1dfdc55402d48bb22 Mon Sep 17 00:00:00 2001
From: "5684185+vsariola@users.noreply.github.com"
 <5684185+vsariola@users.noreply.github.com>
Date: Sun, 22 Sep 2024 09:30:42 +0300
Subject: [PATCH] fix(amd64-386): crash with sample-based oscillator in 32-bit
 library

---
 CHANGELOG.md                                | 2 ++
 vm/compiler/templates/amd64-386/sources.asm | 6 ++++++
 2 files changed, 8 insertions(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 14aeb32..3822211 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -10,6 +10,8 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
   the command line tools.
 
 ### Fixed
+- Crashes with sample-based oscillators in the 32-bit library, as the pointer to
+  sample-table (edi) got accidentally overwritten by detune
 - Sample-based oscillators could hard crash if a x87 stack overflow happened
   when calculating the current position in the sample ([#149][i149])
 - Numeric updown widget calculated dp-to-px conversion incorrectly, resulting in
diff --git a/vm/compiler/templates/amd64-386/sources.asm b/vm/compiler/templates/amd64-386/sources.asm
index 9611c03..558c46c 100644
--- a/vm/compiler/templates/amd64-386/sources.asm
+++ b/vm/compiler/templates/amd64-386/sources.asm
@@ -127,6 +127,9 @@ su_op_oscillat_mono:
 {{- end}}
 {{- if .SupportsParamValueOtherThan "oscillator" "unison" 0}}
     {{.PushRegs .AX "" .WRK "OscWRK" .AX "OscFlags"}}
+{{- if and (not .Amd64) .Library}}
+    push     {{.AX}}                ; pushregs is pushad in 32-bit, and pushes edi last, so decrease SP because library needs to save edi and we can store detune there
+{{- end}}
     fldz                            ; 0 d
     fxch                            ; d a=0, "accumulated signal"
 su_op_oscillat_unison_loop:
@@ -147,6 +150,9 @@ su_op_oscillat_unison_loop:
     dec     eax
     jmp     short su_op_oscillat_unison_loop
 su_op_oscillat_unison_out:
+{{- if and (not .Amd64) .Library}}
+    pop     {{.AX}}                ; pushregs is pushad in 32-bit, and pushes edi last, so we inscrease SP to avoid destroying edi
+{{- end}}
     {{.PopRegs .AX .WRK .AX}}
     ret
 su_op_oscillat_single: