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63 lines
968 B
Markdown
63 lines
968 B
Markdown
---
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title: "cmoc"
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aliases:
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tags:
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- cosc204
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---
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CMOC is a 6809 c compiler.
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it compiles c code into 6809 assembly
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callling conventions
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- A routine must preserve Y, U, S and DP
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- A routine may change A, B, X and CC
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- Parameters are pushed on the stack in the reverse order
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- The caller pops them off the stack after the call
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- char parameters are promoted to int
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- unsigned char are promoted to unsigned int
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- Return 8-but values in B
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- Return 16-bit values in D
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# examples
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parameters
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``` c
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uint16_t two_params(uint8_t first, uint16_t second) {
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return first + second;
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}
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uint16_t call_one(void) {
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return two_params(204, 431);
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}
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```
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```
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```
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local variables
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``` c
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uint16_t one_param(uint16_t xyzzy) {
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uint16_t val = xyzzy;
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return val;
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}
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```
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```
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_one_param
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PSHS U
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LEAU ,S
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LEAS -2,S
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* Formal parameter(s):
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* 4,U: 2 bytes: xyzzy
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* Local non-static variable(s):
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* -2,U: 2 bytes: val
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LDD 4,U
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STD -2,U
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LEAS ,U
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PULS U,PC
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```
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