feat: add while loops

1 files changed, 14 insertions, 1 deletions

diff --git a/docs/language.md b/docs/language.md
index 3ccdab8..8556c8b 100644
--- a/docs/language.md
+++ b/docs/language.md
@@ -120,12 +120,14 @@ loop:               // label
 goto loop
 if rcx != 0         // == != < <= > >= ; guards the next statement or a { block }
     goto loop
+while rcx != 0      // same condition; repeats the next statement or { block }
+    rcx -= 1
 syscall
 print_number(r12)   // call; args go into the callee's parameter registers
 stack buf[Point.size] // stack buffer (size is any constant); buf is its base address
 ```
 
-## Branching (`if` / `else`)
+## Control flow (`if` / `else` / `while`)
 
 `if <expr> <cmp> <expr>` guards either the single next statement or a `{ }` block, and an optional `else` takes its own statement or block. `else if` chains because the `else` body is itself a statement. Comparisons are `==` `!=` `<` `<=` `>` `>=`; a float compare needs an `xmm` register on the left (see [Floating point](#floating-point)).
 
@@ -141,6 +143,17 @@ else
     rdi = -1
 ```
 
+`while <expr> <cmp> <expr>` runs its statement or `{ }` block for as long as the condition holds, testing it before each pass. It is the same condition as `if`, and desugars to a label, the test, the body, and a jump back — the `loop:`/`goto` you would write by hand. Use `goto` to break out early.
+
+```hdass
+rbx = 0
+while rcx > 0
+{
+    rbx += rcx
+    rcx -= 1
+}
+```
+
 ## Dereference (`^`)
 
 `^reg` is the memory at the address in `reg` — NASM's `[reg]`. On the left of `=` it stores there. The store width comes from the value operand, so a sized sub-register picks the size: