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[gamecode] Save and restore data stack in call stack

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This fixes the issue of the data stack not being restored properly
because the returning function needs to return a value from its local
variables (stored on the stack) and accessing stack data below the stack
pointer is a bad idea (sure, no interrupts yet, but who knows...).
This commit is contained in:
Bill Currie 2022-01-17 14:45:14 +09:00
parent 8e5c2c6534
commit 213434b705
2 changed files with 8 additions and 0 deletions
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1
include/QF/progs.h
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@ -1802,6 +1802,7 @@ typedef struct strref_s strref_t;
typedef struct {
pr_uint_t staddr; ///< Return statement.
pr_uint_t stack_ptr; ///< data stack on entry to function
bfunction_t *func; ///< Calling function.
strref_t *tstr; ///< Linked list of temporary strings.
} prstack_t;

7
libs/gamecode/pr_exec.c
View file

@ -143,6 +143,9 @@ PR_PushFrame (progs_t *pr)
frame = pr->pr_stack + pr->pr_depth++;
frame->staddr = pr->pr_xstatement;
if (pr->globals.stack) {
frame->stack_ptr = *pr->globals.stack;
}
frame->func = pr->pr_xfunction;
frame->tstr = pr->pr_xtstr;
@ -179,6 +182,10 @@ PR_PopFrame (progs_t *pr)
pr->pr_xfunction = frame->func;
pr->pr_xstatement = frame->staddr;
pr->pr_xtstr = frame->tstr;
// restore data stack (discard any locals)
if (pr->globals.stack) {
*pr->globals.stack = frame->stack_ptr;
}
}
static __attribute__((pure)) long