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Rett Berg 2019-11-16 12:47:32 -07:00
parent 4727925b1a
commit 0427cb3168
1 changed files with 6 additions and 6 deletions
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wasm.html.markdown
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@ -224,9 +224,9 @@ contributors:
(export "apply_cos64" (func $apply_cos64))
;; Wasm is a stack-based language, but for returning values more complicated
;; than an int/float, a memory stack has to be manually managed. One
;; than an int/float, a separate memory stack has to be manually managed. One
;; approach is to use a mutable global to store the stack_ptr. We give
;; ourselves 1MiB of mem-stack and grow it downwards.
;; ourselves 1MiB of memstack and grow it downwards.
;;
;; Below is a demonstration of how this C code **might** be written by hand
;;
@ -244,7 +244,7 @@ contributors:
;; return s.a + s.b;
;; }
;; Unlike C, we must manage our own memory stack
;; Unlike C, we must manage our own memory stack. We reserve 1MiB
(global $memstack_ptr (mut i32) (i32.const 65536))
;; Structs can only be returned by reference
@ -270,7 +270,7 @@ contributors:
(local $var$sum_struct$b i32)
(local $local_memstack_ptr i32)
;; reserve stack space
;; reserve memstack space
(i32.sub
(get_global $memstack_ptr)
(i32.const 8)
@ -278,7 +278,7 @@ contributors:
tee_local $local_memstack_ptr ;; tee both stores and returns given value
set_global $memstack_ptr
;; call the function, storing the result in the stack
;; call the function, storing the result in the memstack
(call $sum_struct_create
((;$sum_struct_ptr=;) get_local $local_memstack_ptr)
((;$var$a=;) i32.const 40)
@ -293,7 +293,7 @@ contributors:
(i32.load offset=4 (get_local $local_memstack_ptr))
)
;; unreserve stack space
;; unreserve memstack space
(set_global $memstack_ptr
(i32.add
(get_local $local_memstack_ptr)